PCI/MSI: Mask MSI-X vectors only on success

Masking all unused MSI-X entries is done to ensure that a crash kernel
starts from a clean slate, which correponds to the reset state of the
device as defined in the PCI-E specificion 3.0 and later:

 Vector Control for MSI-X Table Entries
 --------------------------------------

 "00: Mask bit:  When this bit is set, the function is prohibited from
                 sending a message using this MSI-X Table entry.
                 ...
                 This bit’s state after reset is 1 (entry is masked)."

A Marvell NVME device fails to deliver MSI interrupts after trying to
enable MSI-X interrupts due to that masking. It seems to take the MSI-X
mask bits into account even when MSI-X is disabled.

While not specification compliant, this can be cured by moving the masking
into the success path, so that the MSI-X table entries stay in device reset
state when the MSI-X setup fails.

[ tglx: Move it into the success path, add comment and amend changelog ]

Fixes: aa8092c1

 ("PCI/MSI: Mask all unused MSI-X entries")                                                                                                                                                                                                                 
Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-pci@vger.kernel.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Marek Vasut <marex@denx.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211210161025.3287927-1-sr@denx.de