kbuild: fix argument parsing in scripts/config

The script previously assumed --file was always the first argument,
which caused issues when it appeared later. This patch updates the
parsing logic to scan all arguments to find --file, sets the config
file correctly, and resets the argument list with the remaining
commands.

It also fixes --refresh to respect --file by passing KCONFIG_CONFIG=$FN
to make oldconfig.

Signed-off-by: Seyediman Seyedarab <imandevel@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>