Merge pull request #25 from mazgch/master

C027 specific interface changes
Fixed compile error when BOARD_UBLOX_C027 not set
Merge pull request #26 from toyowata/master

Fixed compile error when BOARD_UBLOX_C027 is not set
- allow to enter the NXP ISP by pressing the push button
- need to be in privileged mode when entering ISP (use SVC_2)