riscv: dts: microchip: remove icicle memory clocks

The clock properties in the icicle kit's memory entries cause dtbs_check
errors:
arch/riscv/boot/dts/microchip/microchip-mpfs-icicle-kit.dtb: /: memory@80000000: 'clocks' does not match any of the regexes: 'pinctrl-[0-9]+'

Get rid of the clocks to avoid the errors.

Reported-by: Palmer Dabbelt <palmer@rivosinc.com>
Fixes: 0fa6107e ("RISC-V: Initial DTS for Microchip ICICLE board")
Fixes: 5b28df37

 ("riscv: dts: microchip: update peripherals in icicle kit device tree")
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220509142610.128590-2-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>