Implement support for early printf. You need to define SOCDEV_{PA,VA}
as described in the comments for the eputc function in your config file.
Clean up HL201 config (for the hot-e 201 and 101 models from thinlinx).
Make comments match parameters
Add options for early printf so we get regression build testing on it.
Add preview of options for FDT support coming soon (I hope)
Mostly revert r260267 and hopefully really fix the original problem.

The latest draft of SBC-3 tells: "A MAXIMUM UNMAP LBA COUNT field set to
a non-zero value indicates the maximum number of LBAs that may be unmapped
by an UNMAP command."  To me it does not sound like that limit is set per
single descriptor, but rather per all command.  And I have at least one
device that behaves exactly that way.  This patch fixes the problem there.

MFC after:	1 week
Document EARLY_PRINTF