firmware: arm_sdei: Remove sdei_is_err()

sdei_is_err() is only called by sdei_to_linux_errno(). The logic of
checking on the error number is common to them. They can be combined
finely.

This removes sdei_is_err() and its logic is combined to the function
sdei_to_linux_errno(). Also, the assignment of @err to zero is also
dropped in invoke_sdei_fn() because it's always overridden afterwards.
This shouldn't cause functional changes.
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20200922130423.10173-2-gshan@redhat.comSigned-off-by: Will Deacon <will@kernel.org>

drivers/firmware/arm_sdei.c

@@ -114,26 +114,7 @@ static int sdei_to_linux_errno(unsigned long sdei_err)
 		return -ENOMEM;
 	}
 
-	/* Not an error value ... */
-	return sdei_err;
-}
-
-/*
- * If x0 is any of these values, then the call failed, use sdei_to_linux_errno()
- * to translate.
- */
-static int sdei_is_err(struct arm_smccc_res *res)
-{
-	switch (res->a0) {
-	case SDEI_NOT_SUPPORTED:
-	case SDEI_INVALID_PARAMETERS:
-	case SDEI_DENIED:
-	case SDEI_PENDING:
-	case SDEI_OUT_OF_RESOURCE:
-		return true;
-	}
-
-	return false;
+	return 0;
 }
 
 static int invoke_sdei_fn(unsigned long function_id, unsigned long arg0,
@@ -141,14 +122,13 @@ static int invoke_sdei_fn(unsigned long function_id, unsigned long arg0,
 			  unsigned long arg3, unsigned long arg4,
 			  u64 *result)
 {
-	int err = 0;
+	int err;
 	struct arm_smccc_res res;
 
 	if (sdei_firmware_call) {
 		sdei_firmware_call(function_id, arg0, arg1, arg2, arg3, arg4,
 				   &res);
-		if (sdei_is_err(&res))
-			err = sdei_to_linux_errno(res.a0);
+		err = sdei_to_linux_errno(res.a0);
 	} else {
 		/*
 		 * !sdei_firmware_call means we failed to probe or called