x86/efi: Preface all print statements with efi* tag

The pr_*() calls in the x86 EFI code may or may not include a
subsystem tag, which makes it difficult to grep the kernel log for all
relevant EFI messages and leads users to miss important information.

Recently, a bug reporter provided all the EFI print messages from the
kernel log when trying to diagnose an issue but missed the following
statement because it wasn't prefixed with anything indicating it was
related to EFI,

  pr_err("Error ident-mapping new memmap (0x%lx)!\n", pa_memmap);

Cc: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
diff --git a/arch/x86/platform/efi/efi-bgrt.c b/arch/x86/platform/efi/efi-bgrt.c
index ea48449..9a52b5c 100644
--- a/arch/x86/platform/efi/efi-bgrt.c
+++ b/arch/x86/platform/efi/efi-bgrt.c
@@ -10,6 +10,9 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/acpi.h>
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index a0ac0f9..d347e85 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -15,6 +15,8 @@
  *
  */
 
+#define pr_fmt(fmt) "efi: " fmt
+
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/mm.h>
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 1c7380d..6452070 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -1,3 +1,5 @@
+#define pr_fmt(fmt) "efi: " fmt
+
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
@@ -256,7 +258,7 @@
 	 * services.
 	 */
 	if (!efi_runtime_supported()) {
-		pr_info("efi: Setup done, disabling due to 32/64-bit mismatch\n");
+		pr_info("Setup done, disabling due to 32/64-bit mismatch\n");
 		efi_unmap_memmap();
 	}