pinctrl: tegra: avoid duplicate field initializers

The drv_reg field is initialized both in the DRV_PINGROUP_ENTRY_N/DRV_PINGROUP_ENTRY_Y
macros and in DRV_PINGROUP_Y. Since each pingroup expands both macros, the are
always duplicate and turning on -Woverride-init (which is disabled by default)
causes a huge amount of warnings like:

drivers/pinctrl/tegra/pinctrl-tegra234.c:1384:27: error: initialized field overwritten [-Werror=override-init]
 1384 | #define DRV_PINGROUP_Y(r) ((r))
      |                           ^
drivers/pinctrl/tegra/pinctrl-tegra234.c:1397:28: note: in expansion of macro 'DRV_PINGROUP_Y'
 1397 |                 .drv_reg = DRV_PINGROUP_Y(r),                   \
      |                            ^~~~~~~~~~~~~~
drivers/pinctrl/tegra/pinctrl-tegra234.c:1447:49: note: in expansion of macro 'DRV_PINGROUP_ENTRY_Y'
 1447 | #define drive_soc_gpio08_pb0                    DRV_PINGROUP_ENTRY_Y(0x500c,    12,     5,      20,     5,      -1,     -1,     -1,     -1,     0)
      |                                                 ^~~~~~~~~~~~~~~~~~~~
...

Remove the intialization that is never used here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230616161603.1127687-1-arnd@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/tegra/pinctrl-tegra234.c

@@ -1442,7 +1442,6 @@ static const char * const tegra234_functions[] = {
 		.schmitt_bit = schmitt_b,			\
 		.drvtype_bit = 13,				\
 		.lpdr_bit = e_lpdr,				\
-		.drv_reg = -1,					\
 
 /* main drive pin groups */
 #define	drive_soc_gpio08_pb0			DRV_PINGROUP_ENTRY_Y(0x500c,	12,	5,	20,	5,	-1,	-1,	-1,	-1,	0)