msm: kgsl: Print map count instead of map size

/sys/kernel/debug/kgsl/proc/<pid>/mem prints incorrect map size
in some cases. Currently, memdesc size is printed as map size.
Because of this, map size shows non-zero value even for unmapped
buffers. Since kgsl buffers can be mapped multiple times, update
the print to map count instead of map size.

Change-Id: I7970580bc3b1c9a30ca0d72d9caf89af1ce09740
Signed-off-by: Kamal Agrawal <kamaagra@codeaurora.org>