kpatch/LoongArch: fix build error on non-LoongArch architectures

Added conditional compilation to prevent 'R_LARCH_64' and 'EM_LOONGARCH'
from being referenced on x86 and other non-LoongArch architectures. This
ensures the code works across different architectures without errors.

Signed-off-by: George Guo <guodongtai@kylinos.cn>

Author: georgejguo

kpatch-build/kpatch-elf.h

@@ -31,6 +31,11 @@
 #define SHF_RELA_LIVEPATCH	0x00100000
 #define SHN_LIVEPATCH		0xff20
 
+#ifndef __loongarch__
+#define EM_LOONGARCH		258     /* LoongArch */
+#define R_LARCH_64              2
+#endif
+
 /*******************
  * Data structures
  * ****************/