ARM: cleanup undefined instruction entry code

We don't need to keep reloading the thread into into r10 - we can do
this once and keep the value cached in the register.  Also, schedule
some instructions better so that the pipeline doesn't stall after a
load in the neon code.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: Honor udelay convention for timer-based delay

Replaced strict "below" comparison in timer delay function with "below
or equal". The former may result in actual delay time below requested
(if the delay happens to start just before cycle counter advance). The
latter guarantees actual delay at/above requested.

Change-Id: I8cf87836e37647997ca6480c2476255369e8953d
Signed-off-by: Alex Frid <afrid@nvidia.com>
Reviewed-on: http://git-master/r/262858
Reviewed-by: Seshendra Gadagottu <sgadagottu@nvidia.com>
Reviewed-by: Bo Yan <byan@nvidia.com>