Replaced get_tick_per_sec() by NANOSECONDS_PER_SECOND

This patch replaces get_ticks_per_sec() calls with the macro
NANOSECONDS_PER_SECOND. Also, as there are no callers, get_ticks_per_sec()
is then removed.  This replacement improves the readability and
understandability of code.

For example,

    timer_mod(fdctrl->result_timer,
	      qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + (get_ticks_per_sec() / 50));

NANOSECONDS_PER_SECOND makes it obvious that qemu_clock_get_ns
matches the unit of the expression on the right side of the plus.

Signed-off-by: Rutuja Shah <rutu.shah.26@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/dma/rc4030.c b/hw/dma/rc4030.c
index 1c4f8df..a06c235 100644
--- a/hw/dma/rc4030.c
+++ b/hw/dma/rc4030.c
@@ -112,7 +112,7 @@
     tm_hz = 1000 / (s->itr + 1);
 
     timer_mod(s->periodic_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
-                   get_ticks_per_sec() / tm_hz);
+                   NANOSECONDS_PER_SECOND / tm_hz);
 }
 
 /* called for accesses to rc4030 */