Memtest86+: Replace serial accessor macros with inline functions

The macros had a number of problems, including using magic global
variables. (See linux kernel coding style 12.2 for details).
WAIT_FOR_XMITR did not look like a function call.

The easiest solution is to replace them with inline functions. The
global variable 'lsr' may also be removed now.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Change-Id: I5a6995b54b7e84fd1d68dbfa6003a0b1f8cd6067
Reviewed-on: https://review.coreboot.org/c/memtest86plus/+/37057
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2 files changed