tegra124: Re-enable waiting for the transmitter to empty in the test function.

The compiler was emitting code compatible with armv7-a, but the bootblock was
running on a core which uses armv4t. By coincidence, it was emitting an
instruction which is unavailable on armv4t when checking the value of the
UART's LSR register. Now that the bootblock is compiled with more appropriate
flags, this code can be re-introduced.

TEST=Built into the bootblock on nyan and, with the test function enabled, saw
a stream of "!"s on the console.

Change-Id: I7ecada4138b0889b963d1a8b19a4bab8e0bb1add
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/170997
Reviewed-by: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
1 file changed