linux-generic: atomic: implemented exchange
linux-generic: atomic: implemented exchange

Implemented 32 and 64 bit atomic exchange operations.

Signed-off-by: Petri Savolainen <d528fd253b9aaf78fa72edbcc6249e82047f6ce6@nokia.com>
Reviewed-by: Ola Liljedahl <6d19e6e0076f8797cfccb58ffb99074265221b72@linaro.org>
Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>

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