msm: ipa3: fix the Use-after-free in ipa3_dma_destroy

Move the kfree of ipa3_dma_ctx after finishing the
accessing during clean-up.

Change-Id: Ic7c82fd083ecab069e71b4ba21b04dc88cf9dbad
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>