sunxi: fix sid base address macro name for H6

In the current H6 CPU memory space code, the SUNXI in the macro name of
the SID address base is wrongly spelled as SNUXI, which leads to SID
readout not working.

Fix this macro name.

Fixes: 55f6b1c351c9 ("sunxi: add basic memory map definitions of H6 SoC")
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>