iwlwifi: pcie: provide a way to stop configuration if it is forbidden

The firmware debug infrastructure allows the user to
provide a firmware that will toggle a few registers to
configure the debugging capabilities.
On certain devices, certain operations are forbidden.
Executing a forbidden operation will cause the hardware to
die in a way that only driver unload / load will bring it
back to life.
Fortunately, there is a way to know in advance if those
operations will be accepted by the device. This is where
the new PRPH_BLOCKBIT operation plays its role. If the bit
X from PRPH register Y is set, then we should prevent any
further register configuration. When that happens, drop a
line in the kernel log since this is really an error state:
the user won't have his device configured as he expected.
Add operations that will be used in the future:
INDIRECT_ASSIGN, INDIRECT_SETBIT, and INDIRECT_CLEARBIT.

Other debugging configurations (such as destination
configuration for the monitor) will take place in any case.

Signed-off-by: Haim Dreyfuss <haim.dreyfuss@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>