rpb.inc: update GCCVERSION to arm-11.3
rpb.inc: update GCCVERSION to arm-11.3

meta-arm-toolchain updated provided toolchain to 11.3, follow this update.

Signed-off-by: Dmitry Baryshkov <2dcd7ecf02101ef1dca344c0511f3ffb180907c2@linaro.org>

96boards/meta-rpb,96boards/meta-rpb