pcie: pcie_cap_slot_enable_power() use correct helper

pcie: pcie_cap_slot_enable_power() use correct helper

*_by_mask() helpers shouldn't be used here (and that's the only one).
*_by_mask() helpers do shift their value argument, but in pcie.c code
we use values that are already shifted appropriately.
Happily, PCI_EXP_SLTCTL_PWR_ON is zero, so shift doesn't matter. But if
we apply same helper for PCI_EXP_SLTCTL_PWR_OFF constant it will do
wrong thing.

So, let's use instead pci_word_test_and_clear_mask() which is already
used in the file to clear PCI_EXP_SLTCTL_PWR_OFF bit in
pcie_cap_slot_init() and pcie_cap_slot_reset().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Anton Kuchin <antonkuchin@yandex-team.ru>
Message-Id: <20230216180356.156832-11-vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>