OS_mkdir tests should use valid access settings (even though not implemented yet)

[skliper]

Is your feature request related to a problem? Please describe.
Per note in the API:

osal/src/os/inc/osapi-dir.h

Lines 109 to 111 in 706f0de

	* @note Current implementations do not utilize the "access" parameter. Applications
	* should still pass the intended value (#OS_READ_WRITE or #OS_READ_ONLY) to be compatible
	* with future implementations.

Yet tests don't use sensible values (examples):

osal/src/tests/file-api-test/file-api-test.c

Line 474 in 706f0de

status = OS_mkdir(dir1, 0);

osal/src/unit-tests/osfile-test/ut_osfile_dirio_test.c

Line 170 in 706f0de

if (OS_mkdir(g_dirName, 755) != OS_SUCCESS)

Describe the solution you'd like
Use appropriate values. 755 is definitely not correct and could lead to confusion.

Describe alternatives you've considered
At minimum don't use an incorrect value. 0 is probably least-bad...

Additional context
None

Requester Info
Jacob Hageman - NASA/GSFC