recovery: Support board-specified font sizes and font-files

This, for example, is for an LDPI device:
BOARD_RECOVERY_FONT_INCLUDE_HEADER := ../../device/geeksphone/one/font_7x16.h
BOARD_RECOVERY_FONT_WIDTH := 7
BOARD_RECOVERY_FONT_HEIGHT := 16

Change-Id: I71d2f420b9668b5767c9b0b5d90e3e523c56e873