arm64: dts: broadcom: bcm4908: Fix timer node for BCM4906 SoC

arm64: dts: broadcom: bcm4908: Fix timer node for BCM4906 SoC

[ Upstream commit 065f80d231d66333e30d91200d7922281765267d ]

The cpu mask value in interrupt property inherits from bcm4908.dtsi
which sets to four cpus. Correct the value to two cpus for dual core
BCM4906 SoC.

Fixes: e811fd9669e7 ("arm64: dts: broadcom: bcm4908: add BCM4906 Netgear R8000P DTS files")
Signed-off-by: William Zhang <william.zhang@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>