flash: spi_nor: Convert FLASH_{WRITE,ERASE}_BLOCK_SIZE to DT_
flash: spi_nor: Convert FLASH_{WRITE,ERASE}_BLOCK_SIZE to DT_

Convert generic FLASH_{WRITE,ERASE}_BLOCK_SIZE to driver specific
generated define DT_JEDEC_SPI_NOR_0_{WRITE,ERASE}_BLOCK_SIZE.

Signed-off-by: Kumar Gala <a5e5248af4cd4f0ed8c515f61d40a6e2db46a66e@linaro.org>

galak/zephyr,Vudentz/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,nashif/zephyr,explora26/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,explora26/zephyr,ldts/zephyr,nashif/zephyr,explora26/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,ldts/zephyr,ldts/zephyr,explora26/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr