dw-xdata-pcie: Fix documentation build warns

dw-xdata-pcie: Fix documentation build warns

Fixes documentation build warns related to indentation, text formatting,
and missing reference on toc.

This fix solves the following warnings:

WARNING: Unexpected indentation.
WARNING: Block quote ends without a blank line; unexpected unindent.
WARNING: document isn't included in any toctree

Link: https://lore.kernel.org/linux-next/20210406214615.40cf3493@canb.auug.org.au/
Fixes: e1181b5bbc3c ("Documentation: misc-devices: Add Documentation for dw-xdata-pcie driver")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Link: https://lore.kernel.org/r/42ed2d9d27579291dc7cce89c0164bd9255fe337.1618066164.git.gustavo.pimentel@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>