sensors/bma253: Fix out-of-bounds access
sensors/bma253: Fix out-of-bounds access

Coverity issue 204204.
self_test_axis did not take into account that axis argument could be AXIS_ALL.
In this case stack memory would be corrupted.

mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core