add some error logging to mmcutils
add some error logging to mmcutils

Change-Id: I4c886822e7d47a0b5636bfc656039b171303d4e5

Plain-Andy/android_platform_bootable_recovery,DerTeufel/dualboot_recovery,76Demented/bootable_recovery-,DerTeufel/dualboot_recovery,randomblame/bootable_recovery,kylinmoddev/android_bootable_recovery,kylinmoddev/android_bootable_recovery,randomblame/bootable_recovery,DerTeufel/dualboot_recovery,76Demented/bootable_recovery-,kylinmoddev/android_bootable_recovery,Plain-Andy/android_platform_bootable_recovery,76Demented/bootable_recovery-,InsomniaAOSP/platform_bootable_recovery,Plain-Andy/android_platform_bootable_recovery,DerTeufel/dualboot_recovery,DerTeufel/dualboot_recovery,76Demented/bootable_recovery-,randomblame/bootable_recovery,randomblame/bootable_recovery,InsomniaAOSP/platform_bootable_recovery,Plain-Andy/android_platform_bootable_recovery,InsomniaAOSP/platform_bootable_recovery,kylinmoddev/android_bootable_recovery,InsomniaAOSP/platform_bootable_recovery,randomblame/bootable_recovery,InsomniaAOSP/platform_bootable_recovery,76Demented/bootable_recovery-