ARM: dts: msm: Specify XHCI interrupt moderation from DT for MDMs

XHCI allows interrupt moderation using imod. This is mainly required
for MDMs running with single core to reduce interrupt load on CPU.
Default value in XHCI driver was updated from 160 to 4000 for all
platforms which affects performance on platforms using multi-cores.
Add this change to specify higher imod value for required targets
so that default value in XHCI driver can be restored.

CRs-fixed: 1019219
Change-Id: Ia5e5c81af63b6d318f67b58a84ce1c824b1fd372
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>