ta: os_test: fix trace messages specifiers

Replace printf() occurrences with use of MSG() macro in TA
implementation source and header files. MSG() macro already prints
the function label and the line number hence remove these explicit
arguments from trace messages printed by HALT() macro.

Use PRI* specifiers in trace messages using xMSG() macros.

Add parentheses to function names in trace message where applicable
to explicit these are function labels.

Add an empty line in implementation of DEF_BIGINT() macro to comply
with OP-TEE coding style.

Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Etienne Carriere <etienne.carriere@foss.st.com>