[ARM] Collect Primecell PL01x-based debug implementations together

Several ARM machine implementations used a PL01x primecell compatible
serial port for debugging purposes, and indepdently implemented the low
level debug macros every time.  Provide a common implementation and
convert these implementations to use this version.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
4 files changed