core: bugfix undefined behavior in expand_prel31()
core: bugfix undefined behavior in expand_prel31()

Fixes undefined behavior in expand_prel31() detected with
CFG_CORE_SANITIZE_UNDEFINED=y

ERROR:   [0x0] TEE-CORE: Undefined behavior shift_out_of_bounds at core/arch/arm/kernel/unwind_arm32.c:102 col 42
ERROR:   [0x0] TEE-CORE: Panic at core/kernel/ubsan.c:189 <__ubsan_handle_shift_out_of_bounds>

Tested-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org> (QEMU)
Reviewed-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org>
Signed-off-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os