drm/i915/hwmon: Fix static analysis tool reported issues

Updated i915 hwmon with fixes for issues reported by static analysis tool.
Fixed integer overflow with upcasting.

v2:
- Added Fixes tag (Badal).
- Updated commit message as per review comments (Anshuman).

Fixes: 4c2572f ("drm/i915/hwmon: Expose power1_max_interval")
Reviewed-by: Badal Nilawar <badal.nilawar@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Karthik Poosa <karthik.poosa@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231204144809.1518704-1-karthik.poosa@intel.com

Author: kpoosa

drivers/gpu/drm/i915/i915_hwmon.c

@@ -175,7 +175,7 @@ hwm_power1_max_interval_show(struct device *dev, struct device_attribute *attr,
 	 *     tau4 = (4 | x) << y
 	 * but add 2 when doing the final right shift to account for units
 	 */
-	tau4 = ((1 << x_w) | x) << y;
+	tau4 = (u64)((1 << x_w) | x) << y;
 	/* val in hwmon interface units (millisec) */
 	out = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
 
@@ -211,7 +211,7 @@ hwm_power1_max_interval_store(struct device *dev,
 	r = FIELD_PREP(PKG_MAX_WIN, PKG_MAX_WIN_DEFAULT);
 	x = REG_FIELD_GET(PKG_MAX_WIN_X, r);
 	y = REG_FIELD_GET(PKG_MAX_WIN_Y, r);
-	tau4 = ((1 << x_w) | x) << y;
+	tau4 = (u64)((1 << x_w) | x) << y;
 	max_win = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
 
 	if (val > max_win)