leds: lp50xx: Remove unused field 'num_of_banked_leds' from 'struct lp50xx'

In 'struct lp50xx', the 'num_of_banked_leds' field is only written and
is never used. Moreover, storing such an information in the 'priv'
structure looks pointless, so remove it.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/a0d472ff587d13a2b91ec32c8776061019caab6a.1714324500.git.christophe.jaillet@wanadoo.fr


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