flash Kinetis: split kinetis_chip from kinetis_flash_bank

Kinetis flash driver probed and decoded chip repeatedly for each flash
bank. Bank ordering used global bank number so multi-target
configuration was broken.

The change introduces kinetis_probe_chip() which reads SIM SDID
and SIM FCFG registers, decodes Kinetis series and family
and fills struct kinetis_chip. This probe runs once for all banks.

struct kinetis_chip contains pointers to all flash banks embeded
in the MCU. It simplifies iteration over all or specific MCU banks.

kinetis_probe_chip() generates MCU name and some informational messages
are improved.

Change-Id: I990db5c63ba490667eec0e5459086d83936662fb
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/3924


Tested-by: jenkins
Reviewed-by: Joakim Nohlgård <joakim.nohlgard@eistec.se>
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>