msm: ipa3: Do not configure USB pipes in MHI mode

IPA MHI and IPA USB are use-cases that do not co-exist.
In case of MHI mode, do not configure USB pipes so if USB
composition includes some tethering function, it will not
interfere with MHI functionality.

Change-Id: I2b1d74e27163fd613d289d8436e8907e447ed6b4
Signed-off-by: Ghanim Fodi <gfodi@codeaurora.org>