msm: gsi: add command stats

Add debug statistics for GSI commands in order to
improve debug capabilities

Change-Id: Iee80fd2bf4b549665a12791009f0cf5ecc7653b9
CRs-Fixed: 1079245
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>