regulator: cpr3-regulator: unregister CPR IRQ affinity notifier correctly

Commit b7d5b597 ("regulator: cpr3-regulator: add support for
configuring CPR IRQ affinity") added a call to
register_hotcpu_notifier() but did not add a call to
unregister_hotcpu_notifier().  Correct this so that the IRQ
affinity notifier is unregistered when a cpr3-regulator device
is unregistered.

Change-Id: I6379559e201f14a0fd46c1e06761fae356ec9813
CRs-Fixed: 949650
Signed-off-by: David Collins <collinsd@codeaurora.org>