Revert "usb_drv: Wait for IRQ on SKB exhaustion"

The fix overly influences gigabit ethernet performance (~200 MBit), so,
we need to investigate further.

This reverts commit aacb91f22abc56da291e8c066956f957828c6c08.

Reopen #788.
nova: support to get consumed time of a thread
nova: determine number of CPUs
nova: add native_capability comparator
initial cpu_monitor

* wrap CPU interface
* add cpu_monitor interface
* add test client using cpu_monitor interface
* support for FOC and NOVA
foc: add support to get cpu idle times of kernel
nova: add support to get cpu idle times of kernel
cpu_monitor: provide cpu idle times

works for foc and nova
nova: support setting affinity via cpu session
nova: add affinity to pager object construction
base: add affinity support to pager construction
nova: create pager/server thread on specific cpus
nova: handle main thread also inside context area

Issue #540
nova: show client name for unhandled page faults

ease debugging
nova: map pager cap of main thread to a new PD
nova: delegate exception portals on CPU of caller

Before this commit the exception portals for new threads has been mapped
during the reply from the pager of the new thread. The pager thread may
be located on another CPU as the caller thread - initiation the creation of the
new thread - is running on, so mapping will be denied by the kernel.

Instead map the exception portals on the CPU of the caller thread by calling
its pager and take the pager cap of the new thread as (translate) argument.
The pager code use the translated cap to lookup the pager_object of the new
thread. With that object in hand the pager can map the right exception portals
during the reply.
nova: catch exception when leaving thread::entry()

Catch exceptions and try to make a printf. If this also fails, catch
it and die causing some noise output in core to detect the situation.
base: avoid deadlock if invalid object is called

This avoids a deadlock if during issuing a printf the low level IPC fails.
. Printf uses an address space local lock and if we are trying again
to make a printf we deadlock forever ...
print life signs by main thread of affinity test
base: store initial ax and di registers in crt0.s

The values are used by a follow up commit by nova to get the boot CPU number.