platform: msm_shared: Count the leading zeros in ecc_buf

The leading zeros are not counted once the val becomes
negative after right shifting. Complement the val and
count the number of ones.

Change-Id: I28eee38ac31624330ef0cf7c2ba41a7d8f55ab5a
Signed-off-by: Shreyas K K <shrekk@codeaurora.org>