armv7/exynos5250: Deprecate sdelay in favor of udelay

This gets rid of the clock-tick based sdelay in favor of udelay().
udelay() is more consistent and easier to work with, and this allows
us to carry one less variation of timers (and headers and sources...).

Every 1 unit in the sdelay() argument was assumed to cause a delay of
2 clock ticks (@1.7GHz). So the conversion factor is roughly:
sdelay(N) = udelay(((N * 2) / 1.7 * 10^9) * 10^6)
          = udelay((N * 2) / (1.7 * 10^3))

The sdelay() periods used were:
sdelay(100) --> udelay(1)
sdelay(0x10000) --> udelay(78) (rounded up to udelay(100))

There was one instance of sdelay(10000), which looked like sort of a
typo since sdelay(0x10000) was used elsewhere. sdelay(10000) should
approximate to about 12us, so we'll stick with that for now and leave
a note.

Change-Id: I5e7407865ceafa701eea1d613bbe50cf4734f33e
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/3079
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/cpu/samsung/exynos5250/clock_init.c

@@ -25,7 +25,6 @@
 #include <delay.h>
 #include <stdlib.h>
 #include <types.h>
-#include <system.h>
 
 #include <console/console.h>