spi: spi_amd: Update Kconfig dependencies

Add X86 and SPI_MEM as dependencies for the spi_amd driver to ensure it is
built only on relevant platforms and with the required SPI memory
framework.

Co-developed-by: Akshata MukundShetty <akshata.mukundshetty@amd.com>
Signed-off-by: Akshata MukundShetty <akshata.mukundshetty@amd.com>
Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>
Link: https://patch.msgid.link/20250516100658.585654-4-Raju.Rangoju@amd.com


Signed-off-by: Mark Brown <broonie@kernel.org>