ARM: dts: dra7: remove ti,hwmod property from pcie phy

Now that we don't have hwmod entry for pcie PHY remove the
ti,hwmod property from PCIE PHY's. Otherwise we will get:

platform 4a094000.pciephy: Cannot lookup hwmod 'pcie1-phy'

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
[tony@atomide.com: updated comments]
Signed-off-by: Tony Lindgren <tony@atomide.com>