loader/u-boot: fix alignment of uimage components.

The "blobs" in a U-Boot uimage are aligned at 4 bytes, which we
did not take into account. Found this when adding a 3rd blob
containing the Flattened Device Tree for ARM.
ARM: kernel: fix timer resolution and implement basic timekeeping.

The previously used method for programming the timer did not take
into account that our timespec is 64bit while the register we poke
it into is 32 bit. Since the PXA (SoC in Verdex target) has a limited
scale of resolution (us,ms,second) we dynamicly determine the one
that we can most closely match, and set that.

For f.ex. snooze to work however, we also need system_time to work.
The current implementation uses a system timer at microsecond
resolution to keep track of time.

Although the code is far from perfect, committing it now before
it gets lost, since I'm working on the infrastructure code
to properly factor out the SoC specific code out of the core
ARM architecture code (so the kernel can support more then
our poor old Verdex QEMU target ;))