svf: make command 'svf' syntax consistent
The command 'svf' is the only command in OpenOCD that accepts
options in both forms 'option' and '-option'.
Deprecate the option format without the leading '-'.
Update the documentation and fix the on-line help.
While there:
- switch to use the new nvp.h helper;
- return ERROR_COMMAND_ARGUMENT_INVALID on invalid command args;
- fix some minor coding style rule.
Change-Id: I5b944403d92a3fa1e12d5faafc1d2a139bc16a7d
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7534
Tested-by: jenkins