Kconfig: Remove an impossible condition

ARCH_SUNXI selects BINMAN, so the condition "!BINMAN && ARCH_SUNXI"
is impossible to satisfy.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Acked-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>