msm: ipa: remove SW workaround

Commit cea5c65d9e5c139cecfcb9923f5bcc0a85fc4aa2 added a SW
workaround for a HW bug. The HW bug is fixed on current
versions of IPA core. This commit reverts that workaround.

Change-Id: Ic22c374a3ef7b3f25ade47b10907339c342c26cc
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>