samsung: misc: allows using environmental macros as args in menu commands

samsung: misc: allows using environmental macros as args in menu commands

Function cmd_process() runs commands with directly given list of arguments
but it doesn't expand given environmental variables names as macros.
Command "gpt" as one of arguments expects expanded macro e.g. $partitions
so it needs to be called by function run_command().

Changes:
- extend array mode_name by lower case commands names - used by find_cmd()
- put each command arguments into one string - used by run_command()
- use run_command() instead of cmd_process()

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>