mips: Enable KCSAN

Replaces KASAN_SANITIZE with KCSAN_SANITIZE in
boot/compressed/Makefile.

Fixes: e0a8b93e mips: Enable KCSAN
Signed-off-by: Nemanja Rakovic <nemanja.rakovic@syrmia.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>