mips: traps, add __init to parity_protection_init

It references __initdata and is called only from an __init function:
trap_init. This avoids section mismatches (which I am seeing with gcc
10).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/kernel/traps.c

@@ -1678,7 +1678,7 @@ __setup("nol2par", nol2parity);
  * Some MIPS CPUs can enable/disable for cache parity detection, but do
  * it different ways.
  */
-static inline void parity_protection_init(void)
+static inline __init void parity_protection_init(void)
 {
 #define ERRCTL_PE	0x80000000
 #define ERRCTL_L2P	0x00800000