net: ipa: support a third pulse register

The AP has third pulse generator available starting with IPA v5.0.
Redefine ipa_qtime_val() to support that possibility.  Pass the IPA
pointer as an argument so the version can be determined.  And stop
using the sign of the returned tick count to indicate which of two
pulse generators to use.

Instead, have the caller provide the address of a variable that will
hold the selected pulse generator for the Qtime value.  And for
version 5.0, check whether the third pulse generator best represents
the time period.

Add code in ipa_qtime_config() to configure the fourth pulse
generator for IPA v5.0+; in that case configure both the third and
fourth pulse generators to use 10 msec granularity.

Consistently use "ticks" for local variables that represent a tick
count.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>