efi: Use PTR_ERR_OR_ZERO()

Fix ptr_ret.cocci warnings:

  drivers/firmware/efi/efi.c:610:8-14: WARNING: PTR_ERR_OR_ZERO can be used

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci
Signed-off-by: NVasyl Gomonovych <gomonovych@gmail.com>
Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tyler Baicar <tbaicar@codeaurora.org>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180102181042.19074-4-ard.biesheuvel@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

drivers/firmware/efi/efi.c

@@ -608,7 +608,7 @@ static int __init efi_load_efivars(void)
 		return 0;
 
 	pdev = platform_device_register_simple("efivars", 0, NULL, 0);
-	return IS_ERR(pdev) ? PTR_ERR(pdev) : 0;
+	return PTR_ERR_OR_ZERO(pdev);
 }
 device_initcall(efi_load_efivars);
 #endif