riscv: dts: sifive: Group tuples in interrupt properties

To improve human readability and enable automatic validation, the tuples
in the various properties containing interrupt specifiers should be
grouped.

Fix this by grouping the tuples of "interrupts" and
"interrupts-extended" properties using angle brackets.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>