iwlwifi: pcie: don't disable interrupts for reg_lock

iwlwifi: pcie: don't disable interrupts for reg_lock

The only thing we do touching the device in hard interrupt context
is, at most, writing an interrupt ACK register, which isn't racing
in with anything protected by the reg_lock.

Thus, avoid disabling interrupts here for potentially long periods
of time, particularly long periods have been observed with dumping
of firmware memory (leading to lockup warnings on some devices.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210210135352.da916ab91298.I064c3e7823b616647293ed97da98edefb9ce9435@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>