arch-arm: define different ARMPKGARCH when different CCARGS are used
* without this tune-xscale and tune-arm926ejs were both creating
packages in armv5te feed, but each with different -mtune, with
OEBasicHash enabled it was causing each package to rebuild with new
-mtune after MACHINE switch, but that doesn't make sense with output
stored in the same armv5te feed
* this makes different feed for each -mtune, but more generic one to be
selected with DEFAULTTUNE
* tune-iwmmxt and tune-ep9312 were already using this, just move it
bellow AVAILTUNES and use ARMPKGARCH_tune-foo syntax
* tune-cortexr4 and tune-cortexm3 are using armv7r/armv7m as ARMPKGARCH
because there isn't another tune to use the same -march
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>