mtd: spi-nor: Fix the spi_nor_read() when config SPI_STACKED_PARALLEL is enabled

mtd: spi-nor: Fix the spi_nor_read() when config SPI_STACKED_PARALLEL is enabled

Update the spi_nor_read() function based on the config SPI_FLASH_BAR
and update the length and bank calculation by spliting the memory of
16MB size banks only when the address width is 3byte.
Fix the read issue for 4byte address width by passing the entire
length to the read function.

Fixes: 5d40b3d384 ("mtd: spi-nor: Add parallel and stacked memories support")
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>