tests/net/lib/tls_credentials/ crashed on sam_e70_xplained and frdm_k64f

[yerabolu]

frdm_k64f and sam_e70_xplained are crashing.
Commit ID: 7983606

Output for frdm_k64f:

E#1      @srrsotc05/frdm-03  console output: ***** BUS FAULT *****
E#1      @srrsotc05/frdm-03  console output:   Stacking error
E#1      @srrsotc05/frdm-03  console output:   NXP MPU error, port 3
E#1      @srrsotc05/frdm-03  console output:     Mode: Supervisor, Data Address: 0x20006810
E#1      @srrsotc05/frdm-03  console output:     Type: Write, Master: 0, Regions: 0x8100
E#1      @srrsotc05/frdm-03  console output: ***** Hardware exception *****

Output for sam_e70_xplained

E#1      @srrsotc04/same70-10  console output: ***** MPU FAULT *****
E#1      @srrsotc04/same70-10  console output:   Stacking error
E#1      @srrsotc04/same70-10  console output:   Data Access Violation
E#1      @srrsotc04/same70-10  console output:   MMFAR Address: 0x20406008
E#1      @srrsotc04/same70-10  console output: **** Unknown Fatal Error 2! ****
E#1      @srrsotc04/same70-10  console output: Current thread ID = 0x20400a34
E#1      @srrsotc04/same70-10  console output: Faulting instruction address = 0x1501b7ee
E#1      @srrsotc04/same70-10  console output: Fatal fault in essential thread! Spinning...