arm64: dts: fvp: Remove panel timings

arm64: dts: fvp: Remove panel timings

The simple-panel driver already has hard-coded timings for
"arm,rtsm-display", and as such screams at us for trying to override a
fixed mode from DT. Since the exact values probably don't matter all
that much anyway, just remove the DT node to keep boot quiet.

Link: https://lore.kernel.org/r/2701c187cf8e0762df38f68cc069ec2c29a3b5a9.1626283322.git.robin.murphy@arm.com
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>