ARM: dts: imx6ull-engicam-microgea-rmm: fix report-rate-hz value

The 'report-rate-hz' property for the edt-ft5x06 driver was added and
handled in the Linux kernel by me with patches [1] and [2] for this
specific board.

The v1 upstream version, which was the one applied to the customer's
kernel, used the 'report-rate' property, which was written directly to
the controller register. During review, the 'hz' suffix was added,
changing its handling so that writing the value directly to the register
was no longer possible for the M06 controller.

Once the patches were accepted in mainline, I did not reapply them to
the customer's kernel, and when upstreaming the DTS for this board, I
forgot to correct the 'report-rate-hz' property value.

The property must be set to 60 because this board uses the M06 controller,
which expects the report rate in units of 10 Hz, meaning the actual value
written to the register is 6.

[1] 625f829586ea ("dt-bindings: input: touchscreen: edt-ft5x06: add report-rate-hz")
[2] 5bcee83a406c ("Input: edt-ft5x06 - set report rate by dts property")
Fixes: ffea3cac94ba ("ARM: dts: imx6ul: support Engicam MicroGEA RMM board")
Co-developed-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>