exynos4: hal: include: Exif.h: always keep two decimal places in macros

The APEX macros always rounded to int, losing too much precision. Ensure
that we always keep at least two decimal digits.

The more precise F-number comes from the value recorded by the camera
closed source driver.

Added a new macro APEX_SHUTTER_TO_EXPOSURE(x) (credit to tryptophane).

Change-Id: Ief43c15c6517d8dc48d4d4bc9e93df9eb01e6b91
Merge branch 'cm-10.1' of https://github.com/CyanogenMod/android_hardware_samsung into phablet