Camera: update Japanese translation.

* CYAN-1855: 'Mピクセル' changed to 'メガピクセル'.
  but AOSP string.xml still contains both 'Mピクセル' and 'メガピクセル',
  I won't fix it because it's AOSP issue.
* add missing entries.
* remove 'pref_shutter_speed_default'.

Change-Id: Iba2c7cef8847392ee64eda955f91c25a6c9998a6
Merge "Camera: update Japanese translation." into cm-10.1