leds: mt6370: Remove unused field 'reg_cfgs' from 'struct mt6370_priv'

In 'struct mt6370_priv', the 'reg_cfgs' field is unused. Moreover
'struct reg_cfg' isn't defined anywhere, so remove it.

Found with cppcheck, unusedStructMember.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/e389be5e1012dc05fc2641123883ca3b0747525a.1714328839.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Lee Jones <lee@kernel.org>