MFC r341253, r341328, r342619, r342626, r342707, r342785, r342865

MFC r341253, r341328, r342619, r342626, r342707, r342785, r342865

r341253:
The libstand's panic() appends its own '\n' to the message, so that users of the API
don't need to supply one.

r341328:
loader: create separate lists for fd, cd and hd, merge bioscd with biosdisk

Create unified block IO implementation in BIOS version, like it is done in UEFI
side. Implement fd, disk and cd device lists, this will split floppy devices
from disks and will allow us to have consistent, predictable device naming
(modulo BIOS issues).

r342619:
loader: create bio_alloc and bio_free for bios bounce buffer

We do have 16KB buffer space defined in pxe.c, move it to bio.c and implement
bio_alloc()/bio_free() interface to make it possible to use this space for
other BIOS calls (notably, from biosdisk.c).

r342626:
Add Copyright.

r342707:
i386_parsedev() needs to support fd devices

r342785:
With buggy int13 ah=15, we can mis-identify the floppy devices.

We have no option than trust INT13 ah=08 return code during the init phase.

r342865:
biospci_write_config args were backwards

biospci_write_config args swapped length and value to write. Some
hardware coped just fine, while other hardware had issues.

PR: 155441, 234460