msm: pm: idle-v7 clean up

Legacy platforms are not expected to use the mainline
anymore. Unsupported targets are MSM7X01A, MSM7X25,
MSM7X27, MSM7X30, QSD8X50, MSM8X60, MSM8960,MSM8930,
APQ8064, FSM9XXX, MSM9615, MSM8625, MSM9625, MSM7X27A.

Remove unused code in idle-v7 and its related files.

Change-Id: If1fbf9eead91d3410c5c5e75cb92824b110b1138
Signed-off-by: Venkat Devarasetty <vdevaras@codeaurora.org>