ish5: fast 32-bit division in scale_us2ticks
ish5: fast 32-bit division in scale_us2ticks

The critical section using scale_us2ticks is in __hw_clock_source_set,
which we can optimize as this has 32-bit inupts and outputs.

Make a separate function for this usage, scale_us2ticks_32, to be used
in this critical section.

BUG=b:133190570
BRANCH=none
TEST=tested outputs of scale_us2ticks_32 to make sure they matched the
correct value for 32-bit inputs

Change-Id: I4f0f928327cb686006c5ebf4ef17becc5e921d9e
Signed-off-by: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1677239
Reviewed-by: Paul Fagerburg <d8c44b60afb21c60f56d931aa690ca1cf34910c8@chromium.org>
Reviewed-by: Jett Rink <9d4aef0593e6843318d99df31597fb6153b89787@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec