gpu: drm: amdgpu: Replace mdelay with msleep in cik_pcie_gen3_enable()

cik_pcie_gen3_enable() is only called by cik_common_hw_init(), which is
never called in atomic context.
cik_pcie_gen3_enable() calls mdelay() to busily wait, which is not
necessary.
mdelay() can be replaced with msleep().

This is found by a static analysis tool named DCNS written by myself.
Signed-off-by: NJia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -1476,7 +1476,7 @@ static void cik_pcie_gen3_enable(struct amdgpu_device *adev)
 				tmp |= PCIE_LC_CNTL4__LC_REDO_EQ_MASK;
 				WREG32_PCIE(ixPCIE_LC_CNTL4, tmp);
 
-				mdelay(100);
+				msleep(100);
 
 				/* linkctl */
 				pci_read_config_word(root, bridge_pos + PCI_EXP_LNKCTL, &tmp16);