tests/mem_slab/mslab, tests/mem_slab/mslab_api and tests/mem_slab/mslab_threadsafe tests are crashing on sam_e70_xplained

[spoorthik]

Issue is first seen on commit: c090776

***** Booting Zephyr OS v1.13.0-rc1-54-g3b80998 (delayed boot 1000ms) *****
Running test suite memory_slab
===================================================================
starting test - test_mslab
(1) - Allocate and free 4 blocks in <test_mslab>
***** USAGE FAULT *****
  Unaligned memory access
***** Hardware exception *****
Current thread ID = 0x204046dc
Faulting instruction address = 0x403054
Fatal fault in thread 0x204046dc! Aborting.


Running test suite mslab_api
===================================================================
starting test - test_mslab_kinit
PASS - test_mslab_kinit
===================================================================
starting test - test_mslab_kdefine
PASS - test_mslab_kdefine
===================================================================
starting test - test_mslab_kdefine_extern
***** BUS FAULT *****
  Precise data bus error
  BFAR Address: 0x3dd6deee
***** Hardware exception *****
Current thread ID = 0x20402550
Faulting instruction address = 0x403204
Fatal fault in thread 0x20402550! Aborting.


***** Booting Zephyr OS v1.13.0-rc1-54-g3b80998 (delayed boot 1000ms) *****
Running test suite mslab_threadsafe
===================================================================
starting test - test_mslab_threadsafe
***** BUS FAULT *****
  Precise data bus error
  BFAR Address: 0x449bb540
***** Hardware exception *****
Current thread ID = 0x20400060
Faulting instruction address = 0x402eb4
Fatal fault in thread 0x20400060! Aborting.

[nashif]

fixed