msm: idle_stats: Permit GPU DCVS daemon to configure number of samples

Add a struct member to allow GPU DCVS daemon to configure the number
of samples collected at runtime. This increases the responsiveness
of the daemon in low fps use cases.

Change-Id: Ibbf17c8a81c9bd819d96c16af2f17bc60c999df9
Signed-off-by: Lynus Vaz <lvaz@codeaurora.org>
(cherry picked from commit fdecd1e91f9b211011a6610199219523e5794c68)

Conflicts:

	arch/arm/mach-msm/idle_stats_device.c