msm: kgsl: Add support for efuse based LM ISENSE slope calculation

Slope value to calculate the sensor current for Limits Management feature
could be calculated and fused on devices. Pass this value to GMU firmware
to override the slope calculation during boot.

Change-Id: I9f9cf3cff90ed27bf52bf412291f9b2e9fc4139c
Signed-off-by: Mohammed Mirza Mandayappurath Manzoor <mmandaya@codeaurora.org>