drivers: flash: stm32: fix warnings about format specifiers
drivers: flash: stm32: fix warnings about format specifiers

Newlibc defines off_t as long int. Change %d format specifier
to %ld for logging of offsets.

Signed-off-by: Thomas Schmid <96835dd8bfa718bd6447ccc87af89ae1675daeca@lfence.de>

nashif/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr