PCI/ASPM: Clear the correct bits when enabling L1 substates

PCI/ASPM: Clear the correct bits when enabling L1 substates

In pcie_config_aspm_l1ss(), we cleared the wrong bits when enabling ASPM L1
Substates.  Instead of the L1.x enable bits (PCI_L1SS_CTL1_L1SS_MASK, 0xf), we
cleared the Link Activation Interrupt Enable bit (PCI_L1SS_CAP_L1_PM_SS,
0x10).

Clear the L1.x enable bits before writing the new L1.x configuration.

[bhelgaas: changelog]
Fixes: 683cde44f272 ("PCI/ASPM: Configure L1 substate settings")
Link: https://lore.kernel.org/r/1584093227-1292-1-git-send-email-yangyicong@hisilicon.com
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v4.11+