arm: do not use dmb for armv5
arm: do not use dmb for armv5

Original bug:
https://bugs.linaro.org/show_bug.cgi?id=355
Armv5 fails on compilation dmb instuction.
Use the same thing like linux kernel does.

Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>
Reviewed-and-Tested-by: Yao Zhao <142031de0f689bd52c5f63d4801028d0ce66529a@windriver.com>

mike-holmes-linaro/odp,kalray/odp-mppa,kalray/odp-mppa,rsalveti/odp,kalray/odp-mppa,erachmi/odp,dkrot/odp,dkrot/odp,dkrot/odp,rsalveti/odp,mike-holmes-linaro/odp,nmorey/odp,kalray/odp-mppa,erachmi/odp,kalray/odp-mppa,nmorey/odp,dkrot/odp,rsalveti/odp,kalray/odp-mppa,rsalveti/odp,ravineet-singh/odp,erachmi/odp,nmorey/odp,ravineet-singh/odp,nmorey/odp,erachmi/odp,mike-holmes-linaro/odp,ravineet-singh/odp,ravineet-singh/odp,kalray/odp-mppa,rsalveti/odp,mike-holmes-linaro/odp