arm: mvebu: theadorable: Add test for ctrl-c in PCIe PEX switch test

arm: mvebu: theadorable: Add test for ctrl-c in PCIe PEX switch test

The check for the missing PEX switch can lead to an infinite loop, when
the PCIe device is not found. It is helpful to enable the user to break
out of this boot-loop, to enable booting to the prompt for test cases.
This patch adds a 3 second delay in the error case before rebooting.
The user can press Ctrl-C in this time to abort the boot-loop.

This patch also calls bootcount_inc() before rebooting in the error
case. This is needed to increment the bootcounter, since this function
is called earlier than the main bootcounter increment. Otherwise the
bootcounter will not be incremented in the error case at all.

Signed-off-by: Stefan Roese <sr@denx.de>