msm: mhi_dev: Remove redundant code

MHI will be using IPA for all transfers from host to device
and viceversa. Remove redundant code for non IPA case.

Change-Id: Ibe7146f94dad5baa8faa66a62025a0fae1a48811
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>