mfd: tps65219: Remove an unused field from 'struct tps65219'

mfd: tps65219: Remove an unused field from 'struct tps65219'

Since commit 3df4c6367520 ("mfd: tps65219: Add support for soft shutdown
via sys-off API"), the 'nb' field from 'struct tps65219' is unused.
Remove it.

Also remove the now useless #include <linux/notifier.h> for the same
reason.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/8a264c3a92b8e62c1dadd374f2685030e042eb08.1750530460.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Lee Jones <lee@kernel.org>