utils.bbclass: Fix override ordering for FILESPATH

utils.bbclass: Fix override ordering for FILESPATH

Currently the overrides are being applied backwards. This means something which is
platform specific is overriding something which is machine specific which
is clearly not intended.

This patch corrects the ordering to match the normal expected behaviour of
OVERRIDES.

Secondly, all overrides are being searched for each path in turn. What should
really happen is that we should look for the highest priority override (e.g. distro
or machine) in each layer, then move on to platform/tune (e.g. armv7a) and
then to arch (e.g. arm). This patch therefore also reverses the for loops
to achieve this behaviour and give the result the user would expect.

(From OE-Core rev: 92cbf7eeea553bfa24c7081473fa8bc4ebc1f552)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>