sunxi: introduce NCAT2 generation model

[Okhunjon Sobirjonov]

When NCAT2 generation model's introduced for t113,
the modification in drivers/mmc/sunxi_mmc.c
> + IS_ENABLED(CONFIG_SUNXI_GEN_NCAT2)) && (sdc_no == 2))
in struct mmc *sunxi_mmc_init(int sdc_no) seems to have
some negative side effects, meaning enabling 8-bit mode for MMC2.
Paticularly,  IS_ENABLED(CONFIG_SUNXI_GEN_NCAT2)
should not be used for D1/T113 
since there is not support for 8-bit mode for MMC2 yet.
Therefore, the solution would be to drop this particular
change entirely.

Signed-off-by: Okhunjon Sobirjonov <Okhunjon.Sobirjonov at Mec-electronics.com>