drm/amdgpu/gfx7: Simplify bitmask creation

Signed-off-by: NTom St Denis <tom.stdenis@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c

@@ -1598,13 +1598,7 @@ void gfx_v7_0_select_se_sh(struct amdgpu_device *adev, u32 se_num, u32 sh_num)
  */
 static u32 gfx_v7_0_create_bitmask(u32 bit_width)
 {
-	u32 i, mask = 0;
-
-	for (i = 0; i < bit_width; i++) {
-		mask <<= 1;
-		mask |= 1;
-	}
-	return mask;
+	return (u32)((1ULL<<bit_width)-1);
 }
 
 /**