fix: ensure braces are not interpreted as LAVA macros

Jobs that include boot arguments including braces (`{` and `}`) are
failing because LAVA is treating them as though they are LAVA macros,
and attempting to expand them.

Signed-off-by: Chris Kay <chris.kay@arm.com>
Change-Id: I3afeb755074adf7d60cc7d3baa57eab47ac09d75
1 file changed