firmware: remove orphaned Email

Manuel Estrada Sainz passed away on May 9th 2004, his email account got
deactivated. He was in charge of the firmware_class code, and still got
CC'ed in recent discussions about it.

Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>