esoc: Call the power_off hooks from the reboot notifier

Usually, the power_off hooks of the esoc clients are called
before the modem is powered down. Power down of the modem
is also triggered from the reboot notifier path. Hence, call
the power-off hooks from that path too.

Change-Id: Ie5a68fe15a86ec10dcd1f5499dd2d0415038ad7b
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>