libstagefright: getHFRRatio should return 1 by default

This fixes camera crashes from divide-by-zero. Also, replaced the
workaround introduced in 1b7ac643d2 by a proper fix.

On ENABLE_AV_ENHANCEMENTS path, getHFRRatio returns 1 when 0 is
detected, thus the default value should be 1 not 0. (1 will turn
all multiplication and division into no-op.)

Change-Id: I5020f461011d5903a5d9bea910e11a4af9948e7f
Revert "libstagefright: set frame packing from codec config"

 * With Venus 1.6, this patch causes the decoder to freeze
   during a new CTS case. Since we aren't using frame packing
   anyway, revert this.

This reverts commit 8356ac84fa349554006dfb6696365794a7d3a204.

Change-Id: I661c84727976aab8a81824279ee1a2fefdd5f8a3