pinctrl: bcm: Remove unused struct bcm6328_pingroup

After commit 0e3db163("pinctrl: bcm: Convert drivers to use struct pingroup
and PINCTRL_PINGROUP()"), no one use struct bcm6328_pingroup, so remove it.
Signed-off-by: Yuan Can <yuancan@huawei.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220927133926.103943-1-yuancan@huawei.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/bcm/pinctrl-bcm6328.c

@@ -26,12 +26,6 @@
 #define BCM6328_MUX_OTHER_REG	0x24
 #define  BCM6328_MUX_MASK	GENMASK(1, 0)
 
-struct bcm6328_pingroup {
-	const char *name;
-	const unsigned * const pins;
-	const unsigned num_pins;
-};
-
 struct bcm6328_function {
 	const char *name;
 	const char * const *groups;