ACPI: introduce helper function acpi_has_method()

Introduce helper function acpi_has_method() and use it in a number
of places to simplify code.

[rjw: Changelog]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index e6bd910..ddefa5f 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -51,14 +51,13 @@
 			  void **retyurn_value)
 {
 	long *cap = context;
-	acpi_handle h_dummy;
 
-	if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
-	    ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
+	if (acpi_has_method(handle, "_BCM") &&
+	    acpi_has_method(handle, "_BCL")) {
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
 				  "support\n"));
 		*cap |= ACPI_VIDEO_BACKLIGHT;
-		if (ACPI_FAILURE(acpi_get_handle(handle, "_BQC", &h_dummy)))
+		if (!acpi_has_method(handle, "_BQC"))
 			printk(KERN_WARNING FW_BUG PREFIX "No _BQC method, "
 				"cannot determine initial brightness\n");
 		/* We have backlight support, no need to scan further */
@@ -77,22 +76,20 @@
  */
 long acpi_is_video_device(acpi_handle handle)
 {
-	acpi_handle h_dummy;
 	long video_caps = 0;
 
 	/* Is this device able to support video switching ? */
-	if (ACPI_SUCCESS(acpi_get_handle(handle, "_DOD", &h_dummy)) ||
-	    ACPI_SUCCESS(acpi_get_handle(handle, "_DOS", &h_dummy)))
+	if (acpi_has_method(handle, "_DOD") || acpi_has_method(handle, "_DOS"))
 		video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
 
 	/* Is this device able to retrieve a video ROM ? */
-	if (ACPI_SUCCESS(acpi_get_handle(handle, "_ROM", &h_dummy)))
+	if (acpi_has_method(handle, "_ROM"))
 		video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
 
 	/* Is this device able to configure which video head to be POSTed ? */
-	if (ACPI_SUCCESS(acpi_get_handle(handle, "_VPO", &h_dummy)) &&
-	    ACPI_SUCCESS(acpi_get_handle(handle, "_GPD", &h_dummy)) &&
-	    ACPI_SUCCESS(acpi_get_handle(handle, "_SPD", &h_dummy)))
+	if (acpi_has_method(handle, "_VPO") &&
+	    acpi_has_method(handle, "_GPD") &&
+	    acpi_has_method(handle, "_SPD"))
 		video_caps |= ACPI_VIDEO_DEVICE_POSTING;
 
 	/* Only check for backlight functionality if one of the above hit. */