ARM: dts: am33xx-l4: Add missing touchscreen clock properties

ARM: dts: am33xx-l4: Add missing touchscreen clock properties

When adding support for TI magadc (Magnetic Stripe Reader and ADC), the
MFD driver common to the touchscreen and the ADC got updated to ease the
insertion of a new DT node for the ADC, with its own compatible, clocks,
etc. Commit 235a96e92c16 ("mfd: ti_am335x_tscadc: Don't search the tree
for our clock") removed one compatible specific information which was
the clock name, because the clock was looked up from scratch in the DT
while this hardware block was only fed by a single clock, already
defined and properly filled in the DT.

Problem is, this change was only validated with an am437x-based board,
where the clocks are effectively correctly defined and referenced. But
on am33xx, the ADC clock is also correctly defined but is not referenced
with a clock phandle as it ought to be.

The touchscreen bindings clearly state that the clocks/clock-names
properties are mandatory, but they have been forgotten in one DTSI. This
was probably not noticed in the first place because of the clock
actually existing and the clk_get() call going through all the tree
anyway.

Add the missing clock phandles in the am33xx touchscreen description.

Reported-by: H. Nikolaus Schaller <hns@goldelico.com>
Fixes: 235a96e92c16 ("mfd: ti_am335x_tscadc: Don't search the tree for our clock")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: H. Nikolaus Schaller <hns@goldelico.com>
Message-Id: <20220314163445.79807-1-miquel.raynal@bootlin.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>