usr_sbin/grml-setkeyboard: Fix a couple of shellcheck warnings

usr_sbin/grml-setkeyboard: Fix a couple of shellcheck warnings

- SC2086: Double quote to prevent globbing and word splitting.
- Ignore SC1091: Not following: /etc/grml/script-functions was not specified as input (see shellcheck -x).
- SC2086: Double quote to prevent globbing and word splitting.
- SC2086: Double quote to prevent globbing and word splitting.
- SC2086: Double quote to prevent globbing and word splitting.
- SC2086: Double quote to prevent globbing and word splitting.
- Ignore SC1091: Not following: /etc/sysconfig/keyboard was not specified as input (see shellcheck -x).
- Ignore SC1010: Use semicolon or linefeed before 'fi' (or quote to make it literal).
- Ignore SC1091: Not following: /etc/grml/language-functions was not specified as input (see shellcheck -x).