timer: replace time() with QEMU_CLOCK_HOST

This patch replaces time() function calls with calls to
qemu_clock_get_ns(QEMU_CLOCK_HOST). It makes such requests deterministic
in record/replay mode of icount.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <20150227131102.11912.89850.stgit@PASHA-ISP>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
