MIPS: Kconfig: Fix recursive dependency.

[...]
  HOSTCC  scripts/kconfig/zconf.tab.o
  HOSTLD  scripts/kconfig/conf
arch/mips/Kconfig:2681:error: recursive dependency detected!
arch/mips/Kconfig:2681:	symbol MIPS32_N32 depends on MIPS32_COMPAT
arch/mips/Kconfig:2658:	symbol MIPS32_COMPAT is selected by MIPS32_N32

Introduced by d74473bdf7a4c1ef7ae2b75f585fe5649ac2dcea (MIPS: Compat: Fix
build error if CONFIG_MIPS32_COMPAT but no compat ABI.)

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>