msm: ipa: IPA coalescing changes

Support new IPA coalescing pipe IPA_WAN_COAL_CONS. If coalescing
is enabled, this pipe will become the default pipe and be setup with
its own transfer ring but share an event ring with WAN_CONS. Also adds
a new coalescing ifdef and support coalescing in the RT rule.

Change-Id: I4d09aaa030c427271f59461897354e3a7cf7a563
Signed-off-by: Michael Adisumarta <madisuma@codeaurora.org>