drm/amdgpu: update retry times for psp vmbx wait

Increase the retry loops and replace the constant number with macro.
Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/psp_v13_0.c

@@ -59,6 +59,9 @@ MODULE_FIRMWARE("amdgpu/psp_14_0_0_ta.bin");
 /* Read USB-PD from LFB */
 #define GFX_CMD_USB_PD_USE_LFB 0x480
 
+/* Retry times for vmbx ready wait */
+#define PSP_VMBX_POLLING_LIMIT 20000
+
 /* VBIOS gfl defines */
 #define MBOX_READY_MASK 0x80000000
 #define MBOX_STATUS_MASK 0x0000FFFF
@@ -138,7 +141,7 @@ static int psp_v13_0_wait_for_vmbx_ready(struct psp_context *psp)
 	struct amdgpu_device *adev = psp->adev;
 	int retry_loop, ret;
 
-	for (retry_loop = 0; retry_loop < 70; retry_loop++) {
+	for (retry_loop = 0; retry_loop < PSP_VMBX_POLLING_LIMIT; retry_loop++) {
 		/* Wait for bootloader to signify that is
 		   ready having bit 31 of C2PMSG_33 set to 1 */
 		ret = psp_wait_for(