The math_brute_force test has a link-check-only mode to quickly test if
all math functions are present.
In link-check-only mode, most tests return immediately after kernel
compilation, but some tests also run the kernel and read back the result
data before returning. Running the kernels takes a lot more time,
defeating the purpose of the `-l` mode.
Break out at the start of the main `for` loops in link-check-only mode
instead of returning directly, so that each test can still log its
trailing message (in most cases just a `\n`).
Signed-off-by: Sven van Haastregt <sven.vanhaastregt@arm.com>
