all: Remove the "STATIC" macro and just use "static" instead.

The STATIC macro was introduced a very long time ago in commit
d5df6cd44a.  The original reason for this was
to have the option to define it to nothing so that all static functions
become global functions and therefore visible to certain debug tools, so
one could do function size comparison and other things.

This STATIC feature is rarely (if ever) used.  And with the use of LTO and
heavy inline optimisation, analysing the size of individual functions when
they are not static is not a good representation of the size of code when
fully optimised.

So the macro does not have much use and it's simpler to just remove it.
Then you know exactly what it's doing.  For example, newcomers don't have
to learn what the STATIC macro is and why it exists.  Reading the code is
also less "loud" with a lowercase static.

One other minor point in favour of removing it, is that it stops bugs with
`STATIC inline`, which should always be `static inline`.

Methodology for this commit was:

1) git ls-files | egrep '\.[ch]$' | \
   xargs sed -Ei "s/(^| )STATIC($| )/\1static\2/"

2) Do some manual cleanup in the diff by searching for the word STATIC in
   comments and changing those back.

3) "git-grep STATIC docs/", manually fixed those cases.

4) "rg -t python STATIC", manually fixed codegen lines that used STATIC.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

ports/renesas-ra/mpbthciport.c

@@ -42,10 +42,10 @@
 
 uint8_t mp_bluetooth_hci_cmd_buf[4 + 256];
 
-STATIC mp_sched_node_t mp_bluetooth_hci_sched_node;
-STATIC soft_timer_entry_t mp_bluetooth_hci_soft_timer;
+static mp_sched_node_t mp_bluetooth_hci_sched_node;
+static soft_timer_entry_t mp_bluetooth_hci_soft_timer;
 
-STATIC void mp_bluetooth_hci_soft_timer_callback(soft_timer_entry_t *self) {
+static void mp_bluetooth_hci_soft_timer_callback(soft_timer_entry_t *self) {
     mp_bluetooth_hci_poll_now();
 }
 
@@ -58,7 +58,7 @@ void mp_bluetooth_hci_init(void) {
         );
 }
 
-STATIC void mp_bluetooth_hci_start_polling(void) {
+static void mp_bluetooth_hci_start_polling(void) {
     mp_bluetooth_hci_poll_now();
 }
 
@@ -67,7 +67,7 @@ void mp_bluetooth_hci_poll_in_ms(uint32_t ms) {
 }
 
 // For synchronous mode, we run all BLE stack code inside a scheduled task.
-STATIC void run_events_scheduled_task(mp_sched_node_t *node) {
+static void run_events_scheduled_task(mp_sched_node_t *node) {
     // This will process all buffered HCI UART data, and run any callouts or events.
     mp_bluetooth_hci_poll();
 }