drivers: flash: w25q: Allow to skip SYNC_LOCK/SYNC_UNLOCK

The next commit will use this new
spi_flash_wb_write_protection_set_with_lock() in
spi_flash_wb_write() that already hold the lock.
To prevent a lock we need to skip the SYNC_LOCK when we want
to disable write protection.

Signed-off-by: Olivier Martin <olivier.martin@proglove.de>