This patch backports "spi-realtek-rtl" driver to Kernel 5.10 from 5.12.
"MACH_REALTEK_RTL" is used as a platform name in upstream, but "RTL838X"
is used in OpenWrt, so update the dependency by the additional patch.
Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>