Unify all <machine>/resource.h, unhide PCI_RES_BUS, add CLK, IOMMU and PWR.

[Aleksandr Rybalko]

* Unify all <machine>/resource.h
* unhide PCI_RES_BUS
* add SYS_RES_CLK
* add SYS_RES_IOMMU
* add SYS_RES_PWR

It seems long time ago, resource.h was designed to be used per
machine type to cover difference like presence IOPORTs on x86 and lack it on
other platforms.
As we see now, resource.h on all platforms contain SYS_RES_IOPORT. But, for
example, not all platform has an SYS_RES_GPIO.
Are that platform have no LEDs attached? :)

https://reviews.freebsd.org/D21703

IMO, same we should do for FDT/OFW, since gpios, clks, power-domains are
widely used, but ePAPR stacks in 2011.

Comments are welcomed.

Thanks!