pwm: tegra: Fix 32 bit build

[ Upstream commit dd1f1da ]

The value of NSEC_PER_SEC << PWM_DUTY_WIDTH doesn't fix within a 32 bit
integer causing a build warning/error (and the value truncated):

  drivers/pwm/pwm-tegra.c: In function ‘tegra_pwm_config’:
  drivers/pwm/pwm-tegra.c:148:53: error: result of ‘1000000000 << 8’ requires 39 bits to represent, but ‘long int’ only has 32 bits [-Werror=shift-overflow=]
    148 |   required_clk_rate = DIV_ROUND_UP_ULL(NSEC_PER_SEC << PWM_DUTY_WIDTH,
        |                                                     ^~

Explicitly cast to a u64 to ensure the correct result.

Fixes: cfcb68817fb3 ("pwm: tegra: Improve required rate calculation")
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Steven Price

drivers/pwm/pwm-tegra.c

@@ -142,7 +142,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		 * source clock rate as required_clk_rate, PWM controller will
 		 * be able to configure the requested period.
 		 */
-		required_clk_rate = DIV_ROUND_UP_ULL(NSEC_PER_SEC << PWM_DUTY_WIDTH,
+		required_clk_rate = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC << PWM_DUTY_WIDTH,
 						     period_ns);
 
 		err = clk_set_rate(pc->clk, required_clk_rate);