pinctrl: qcom: spmi-gpio: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1].

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-throughSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200716212213.GA17623@embeddedorSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/qcom/pinctrl-spmi-gpio.c

@@ -793,13 +793,13 @@ static int pmic_gpio_populate(struct pmic_gpio_state *state,
 	switch (subtype) {
 	case PMIC_GPIO_SUBTYPE_GPIO_4CH:
 		pad->have_buffer = true;
-		/* Fall through */
+		fallthrough;
 	case PMIC_GPIO_SUBTYPE_GPIOC_4CH:
 		pad->num_sources = 4;
 		break;
 	case PMIC_GPIO_SUBTYPE_GPIO_8CH:
 		pad->have_buffer = true;
-		/* Fall through */
+		fallthrough;
 	case PMIC_GPIO_SUBTYPE_GPIOC_8CH:
 		pad->num_sources = 8;
 		break;

drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c

@@ -346,7 +346,7 @@ static int pm8xxx_pin_config_set(struct pinctrl_dev *pctldev,
 				return -EINVAL;
 			}
 			pin->pull_up_strength = arg;
-			/* FALLTHROUGH */
+			fallthrough;
 		case PIN_CONFIG_BIAS_PULL_UP:
 			pin->bias = pin->pull_up_strength;
 			banks |= BIT(2);