i386 removal, part 39/x: Remove est(4) driver.

i386 removal, part 39/x: Remove est(4) driver.

Of the 36 CPUs it supports, only one supports Intel 64 (aka AMD64),
namely the Intel Core 2 Duo T7500, released in May 2007. The rest,
Intel Pentium Ms and two Intel Core CPUs, were 32 bit only.

If someone is still using a T7500 with DragonFly and our regular
ACPI P-state support doesn't work with it, we'd be interested in
hearing about it. As a last resort, there's always cpucontrol(8)
to set the MSRs manually. :)

Also, estd isn't in ports or dports.