[DRIVERS] Use vmm_inb and vmm_outb to access uart

Since on x86 UART is IO mapped, vmm_in_8 et all won't
work on x86. Change the access to vmm_inb which uses
I/O space instructions on x86 and does MMIO on other
architectures.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Make serial port as default console.

Make serial port as the default console for x86.
It can be overridden to use STDIO by having
console=stdio in the command line.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Fix compilation and Enable 8250 code.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] HPET: BUG_ON on single try is overkill

Makes sense especially with HPET to retry for few times.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Paged real mode page tables and some more intercepts.

o Added 32-bit shadow pagetable support (only adding entries)
  for guest booting in paged real mode.
o Guests registers set to point to the reset vector so that
  bios loaded at a specified address maps correctly to which
  xvisor will get page faults in paged real mode.
o Added some more intercepts viz CRn read/write (enable them).

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Minor Fix: Change uncontional print to a debug log.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Remove svm launch file and make things inline

Since vmsave/vmrun, non of them, don't save any
GPRs except for RAX, the launcher function needs
to save it. Passing multiple arguments to a seperate
function doesn't make sense to inlined the complete
svm_launch in svm_run.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>