PCI: hotplug/shpchp_hpc: add parenthesis in SLOT_REG_RSVDZ_MASK

The SLOT_REG_RSVDZ_MASK macro is normally used like this:
	slot_reg &= ~SLOT_REG_RSVDZ_MASK;
The ~ operator has higher precedence than the | operator from inside the
macro, so it needs parenthesis.

Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>