helper: nvp: add openocd nvp files

helper: nvp: add openocd nvp files

Long ago jim_nvp was part of jimtcl. When jimtcl dropped it,
OpenOCD kept copy of it in its code base. Current code of jim_nvp
is still related with jimtcl data types and functions.

With the target of better isolating OpenOCD code from jimtcl,
create a new file nvp.c that re-proposes only the core of the old
jim_nvp, dropping any link with jimtcl and removing the string
'jim' either from the filename and from the code.
Keep the same license from the old code, as the new files are
clearly derived from it.

Change-Id: I273448cf1f1484b10f6b6113ed7bb0fcf946482b
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7423
Tested-by: jenkins
Reviewed-by: Evgeniy Didin <didin@synopsys.com>