msm: kgsl: Store GMU firmware image in the GMU device structure

Use the struct firmware structure for storing the GMU firmware image.
Parse the firmware until out of data rather than reading the number
of blocks present in the firmware.

Change-Id: I6d8aef7a088f26be7fd6f092eedbbe021bf76f77
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>