diag: Switch to correct logging mode after mdlog exit

Mdlog in multimode when exits is not switching to required
USB or PCIE mode. Adding missing check handles switching to
proper logging mode when mdlog exits.

Change-Id: I7c7bc23c463cc809765b4774fa5147c7245d8c50
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>