stm32: flash: BSY bit has never been writable.

This has been copied around for years, but has never been a writable bit
on any target.

include/libopencm3/stm32/common/flash_common_f01.h

@@ -105,7 +105,6 @@ void flash_lock(void);
 void flash_clear_pgerr_flag(void);
 void flash_clear_eop_flag(void);
 void flash_clear_wrprterr_flag(void);
-void flash_clear_bsy_flag(void);
 void flash_clear_status_flags(void);
 uint32_t flash_get_status_flags(void);
 void flash_wait_for_last_operation(void);

include/libopencm3/stm32/common/flash_common_f234.h

@@ -79,7 +79,6 @@ void flash_unlock(void);
 void flash_lock(void);
 void flash_clear_pgperr_flag(void);
 void flash_clear_eop_flag(void);
-void flash_clear_bsy_flag(void);
 void flash_clear_status_flags(void);
 void flash_wait_for_last_operation(void);
 

include/libopencm3/stm32/f1/flash.h

@@ -111,7 +111,6 @@ void flash_lock_upper(void);
 void flash_clear_pgerr_flag_upper(void);
 void flash_clear_eop_flag_upper(void);
 void flash_clear_wrprterr_flag_upper(void);
-void flash_clear_bsy_flag_upper(void);
 
 END_DECLS
 

include/libopencm3/stm32/f7/flash.h

@@ -50,8 +50,6 @@
  * 	by F7 require more than 7 wait states.
  * 4. 	FLASH_SR_PGSERR (programming sequence error) is now FLASH_SR_ERSERR (
  *	erase sequence error).
- * 5. 	FLASH_SR_BSY field is now read-only. Seems to also be read-only in F4?
- *	Why did we have a clear busy flag function?
  * 6. 	There are now two watchdogs - IWDG (independent watchdog) and WWDG (
  * 	window watchdog).
  */

include/libopencm3/stm32/l4/flash.h

@@ -227,7 +227,6 @@ void flash_unlock(void);
 void flash_lock(void);
 void flash_clear_pgperr_flag(void);
 void flash_clear_eop_flag(void);
-void flash_clear_bsy_flag(void);
 void flash_wait_for_last_operation(void);
 void flash_dcache_enable(void);
 void flash_dcache_disable(void);