dw-xdata-pcie: Update outdated info and improve text format

Removes old information related to the stop file interface in sysfs left
by mistake during patch revision.

Improves the document text format to be more user-friendly and adds
basic driver related information, such as support, datasheet, and author.

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Link: https://lore.kernel.org/r/4e72f931474a784d478e5a67961ecf116911997a.1618066164.git.gustavo.pimentel@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>