msm: gsi: Fix compile warnings

Fix the following compiler warning(s) from gcc 6.1.1 with -Werror enabled:

 drivers/platform/msm/gsi/gsi.c:3230:
   format '%lu' expects argument of type 'long unsigned int', but argument 7
     has type 'int' [-Werror=format=]
   GSIDBG("ch=%lu ev=%lu RP=0x%llx WP=0x%llx RP_LOCAL=0x%llx\n",

Fixes: a68620c2 ("msm: ipa: GSI coalescing changes")
Change-Id: Ic0dedbad1af31a5c932d5ddbd8685a3bf9038d68
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>