x86/efi: parse_efi_setup() build fix

In case without CONFIG_EFI, there will be below build error:

   arch/x86/built-in.o: In function `setup_arch':
  (.init.text+0x9dc): undefined reference to `parse_efi_setup'

Thus fix it by adding blank inline function in asm/efi.h
Also remove an unused declaration for variable efi_data_len.
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

arch/x86/include/asm/efi.h

@@ -142,8 +142,6 @@ struct efi_setup_data {
 };
 
 extern u64 efi_setup;
-extern u32 efi_data_len;
-extern void parse_efi_setup(u64 phys_addr, u32 data_len);
 
 #ifdef CONFIG_EFI
 
@@ -153,7 +151,7 @@ static inline bool efi_is_native(void)
 }
 
 extern struct console early_efi_console;
-
+extern void parse_efi_setup(u64 phys_addr, u32 data_len);
 #else
 /*
  * IF EFI is not configured, have the EFI calls return -ENOSYS.
@@ -165,6 +163,7 @@ extern struct console early_efi_console;
 #define efi_call4(_f, _a1, _a2, _a3, _a4)		(-ENOSYS)
 #define efi_call5(_f, _a1, _a2, _a3, _a4, _a5)		(-ENOSYS)
 #define efi_call6(_f, _a1, _a2, _a3, _a4, _a5, _a6)	(-ENOSYS)
+static inline void parse_efi_setup(u64 phys_addr, u32 data_len) {}
 #endif /* CONFIG_EFI */
 
 #endif /* _ASM_X86_EFI_H */