Autodetect 1 or 2 flash blocks devices and recheck bank sizes. Correct pf_size calculation for 2 MB devices. Change-Id: Ib3b68db9ec5356b8d5dc73c9f12053f7476bf474 Signed-off-by: Tomas Vanek <vanekt@fbl.cz> Reviewed-on: http://openocd.zylin.com/2992 Tested-by: jenkins