hwpstate_intel(4): small text tweaks

The sysctl output looks like this:

dev.hwpstate_intel.0.epp: 50
dev.hwpstate_intel.0.%parent: cpu0
dev.hwpstate_intel.0.%pnpinfo:
dev.hwpstate_intel.0.%location:
dev.hwpstate_intel.0.%driver: hwpstate_intel
dev.hwpstate_intel.0.%desc: Intel Speed Shift

but all the '%' got escaped in the manual page, un-escape them.

While here:

• Move the example of dev.hwpstate_intel.%d.%parent after the description to align with others.
• Capitalize "CPU" (*)

Submitted by: danfe (*)
Reviewed by: cem
Differential Revision: https://reviews.freebsd.org/D24520