I.MX6+ version of the silicon exposed PCIe core's reset signal as a bit
in one of the control registers. As a result using old, pre-i.MX6+,
reset sequence on i.MX6+ leads to Barebox hanging during startup. Using
exposed reset bit instead solves the problem.

This commit is based on portions of commit

c34068d

in http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Acked-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>