drm/amdgpu: Fix gfx9 update PTE mtype flag

Fix copy&paste error, that should have been an assignment instead of an or,
otherwise MTYPE_UC 0x3 can not be updated to MTYPE_RW 0x1.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit fc13660)
Cc: stable@vger.kernel.org

Author: amd-yangp

drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c

@@ -1235,16 +1235,16 @@ static void gmc_v9_0_get_vm_pte(struct amdgpu_device *adev,
 		*flags = AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_NC);
 		break;
 	case AMDGPU_VM_MTYPE_WC:
-		*flags |= AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_WC);
+		*flags = AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_WC);
 		break;
 	case AMDGPU_VM_MTYPE_RW:
-		*flags |= AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_RW);
+		*flags = AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_RW);
 		break;
 	case AMDGPU_VM_MTYPE_CC:
-		*flags |= AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_CC);
+		*flags = AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_CC);
 		break;
 	case AMDGPU_VM_MTYPE_UC:
-		*flags |= AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_UC);
+		*flags = AMDGPU_PTE_MTYPE_VG10(*flags, MTYPE_UC);
 		break;
 	}