board: arm64: fvp_baser_aemv8r_smp: Increase CONFIG_MAX_THREAD_BYTES

Increase CONFIG_MAX_THREAD_BYTES to 3 to fix the build issue on
tests/drivers/build_all/modem/ test case.

Signed-off-by: Jaxson Han <[email protected]>
Change-Id: I6a26955bdd7e8b176894fa8246aec63a3a3db05f
(cherry picked from commit a483828)

Author: povergoing

boards/arm64/fvp_baser_aemv8r/fvp_baser_aemv8r_smp_defconfig

@@ -33,3 +33,5 @@ CONFIG_PM_CPU_OPS_PSCI=n
 CONFIG_SOC_FVP_AEMV8R_EL2_INIT=y
 
 CONFIG_MP_NUM_CPUS=4
+
+CONFIG_MAX_THREAD_BYTES=3