include: zephyr: sys: correct sys_test_bit() and friends description

Correct the documentation of sys_test_bit() and its derivative helper
functions (listed below) since these return a bit mask value instead of
an essentially boolean value as previosuly described.

In tree implementation do conform with that: the result of these
functions are always implicitly tested against being 0 or a non-zero
value.

Helper functions which documentation is modified are sys_test_bit(),
sys_test_and_set_bit(), sys_test_and_clear_bit(), sys_bitfield_test_bit(),
sys_bitfield_test_and_set_bit() and sys_bitfield_test_and_clear_bit().

Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
1 file changed