pinctrl: renesas: Replace ifdeffery with IS_ENABLED()

Switch ifdef in sh_gpio_get_value() to IS_ENABLED() macro.
The CONFIG_RCAR_GEN3 will never have SPL counterpart, so
the IS_ENABLED() macro is the right one here. No functional
change, except for improved build test coverage.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/drivers/gpio/sh_pfc.c b/drivers/gpio/sh_pfc.c
index 988f7e9..92522b6 100644
--- a/drivers/gpio/sh_pfc.c
+++ b/drivers/gpio/sh_pfc.c
@@ -568,10 +568,10 @@
 
 	if (!gpioc || get_data_reg(gpioc, gpio, &dr, &bit) != 0)
 		return -1;
-#if defined(CONFIG_RCAR_GEN3)
-	if ((gpioc->gpios[gpio].flags & PINMUX_FLAG_TYPE) == PINMUX_TYPE_INPUT)
+
+	if (IS_ENABLED(CONFIG_RCAR_GEN3) &&
+	    ((gpioc->gpios[gpio].flags & PINMUX_FLAG_TYPE) == PINMUX_TYPE_INPUT))
 		offset += 4;
-#endif
 
 	return gpio_read_bit(dr, offset, bit);
 }