MIPS: Kconfig: Fix indentation for kexec-related entries

Kconfig entries are not aligned properly, so remove incorrect whitespace.
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14631/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>