ARM: 6486/1: provide zero vmcore_elf64_check_arch()

Since we don't support 64-bit ELF vmcores. This also prevents the
following warning:

fs/proc/vmcore.c: In function 'parse_crash_elf64_headers':
fs/proc/vmcore.c:502: warning: passing argument 1 of 'elf_check_arch'
  from incompatible pointer type
Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/elf.h

@@ -99,6 +99,8 @@ struct elf32_hdr;
 extern int elf_check_arch(const struct elf32_hdr *);
 #define elf_check_arch elf_check_arch
 
+#define vmcore_elf64_check_arch(x) (0)
+
 extern int arm_elf_read_implies_exec(const struct elf32_hdr *, int);
 #define elf_read_implies_exec(ex,stk) arm_elf_read_implies_exec(&(ex), stk)