drm/amdgpu: Change the virtual_display type from int to char*.

For virtual display feature, as there may be multiple GPUs,
for user could choose whiche GPU need to enable this feature, change
the type of virtual_display from int to char*. The variable will be set
like this virtual_display="xxxx:xx:xx.x;xxxx:xx:xx.x;".

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 54f7156..46f250c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -92,7 +92,7 @@
 extern unsigned amdgpu_pg_mask;
 extern char *amdgpu_disable_cu;
 extern int amdgpu_sclk_deep_sleep_en;
-extern int amdgpu_virtual_display;
+extern char *amdgpu_virtual_display;
 
 #define AMDGPU_WAIT_IDLE_TIMEOUT_IN_MS	        3000
 #define AMDGPU_MAX_USEC_TIMEOUT			100000	/* 100 ms */
@@ -2072,6 +2072,7 @@
 	atomic_t			gpu_reset_counter;
 
 	/* display */
+	bool				enable_virtual_display;
 	struct amdgpu_mode_info		mode_info;
 	struct work_struct		hotplug_work;
 	struct amdgpu_irq_src		crtc_irq;