linker: fix shared interrupts for MWDT toolchain

MWDT toolchain adds additional suffix to sections name in case of
ffunction-sections / fdata-sections are enabled.

Let's pick a single set of rules and syntax that work for all
toolchain.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>