[MIPS] Don't use R10000 llsc workaround version for all llsc-full processors.

Found and original patch by [e-mail].

Signed-off-by: Ralf Baechle <[e-mail]>

include/asm-mips/system.h

···
 {
 	__u64 retval;
 
-	if (cpu_has_llsc) {
+	if (cpu_has_llsc && R10000_LLSC_WAR) {
 		__asm__ __volatile__(
 		"	.set	push					\n"
 		"	.set	noat					\n"