PCI: iproc: Delete unnecessary checks before phy calls

The functions phy_exit() and phy_power_off() test whether their argument is
NULL and then return immediately.  Thus the test around the calls is not
needed.

This issue was detected by using the Coccinelle software.

[bhelgaas: also phy_init() and phy_power_on(), as Ray Jui suggested]
[bhelgaas: also remove tests in iproc_pcie_remove()]
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>