nvs: fix initialization of fs->data_wra on alignment change
nvs: fix initialization of fs->data_wra on alignment change

When existing records stored in the NVS are not properly
aligned according to the current flash driver requirements,
fs->data_wra may be initialized with an unaligned address.
Fix the initialization code, so that fs->data_wra is rounded
up to the nearest multiple of the current flash driver block
size.

The situation may occur during a firmware upgrade which
introduces a new flash driver or changes its parameters.

Signed-off-by: Damian Krolik <e2fe6fe1e6b356a130ab0d30147444bb6e61419d@nordicsemi.no>

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