mtd: nand: Drop explicit test for built-in CONFIG_SPI_QPIC_SNAND

mtd: nand: Drop explicit test for built-in CONFIG_SPI_QPIC_SNAND

If CONFIG_SPI_QPIC_SNAND=m, but CONFIG_MTD_NAND_QCOM=n:

    ERROR: modpost: "qcom_nandc_unalloc" [drivers/spi/spi-qpic-snand.ko] undefined!
    ...

Fix this by dropping the explicit test for a built-in
CONFIG_SPI_QPIC_SNAND completely.  Kbuild handles multiple and mixed
obj-y/obj-m rules for the same object file fine.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202503280759.XhwLcV7m-lkp@intel.com/
Fixes: 7304d1909080ef0c ("spi: spi-qpic: add driver for QCOM SPI NAND flash Interface")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>