mips: mtmips: spl/Kconfig: Set CONFIG_SPL_PAD_TO to 0x0 for ARCH_MTMIPS

It was noticed that while converting CONFIG_SPL_PAD_TO to Kconfig its
value for the MIPS MT762x/8x targets got not ported correctly. Its
default is not 0x10000 instead of 0x0. This patch fixes this issue.

Fixes: ca8a329a ("Convert CONFIG_SPL_PAD_TO et al to Kconfig")
Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Ruben Winters <Ruben.Winters@gooiland-elektro.nl>
Cc: Weijie Gao <weijie.gao@mediatek.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Tom Rini <trini@konsulko.com>