arm64: dts: imx93: Fix the micfil clock-names entries

fsl,micfil.yaml defines the clock-names in the following sequence:

  clock-names:
    items:
      - const: ipg_clk
      - const: ipg_clk_app
      - const: pll8k
      - const: pll11k
      - const: clkext3
    minItems: 2

imx93.dtsi currently misses the 'pll11k' entry and jump to 'clkext3'.

This leads to the following dt-schema warning:

imx93-11x11-evk.dtb: micfil@44520000: clock-names:3: 'pll11k' was expected
	from schema $id: http://devicetree.org/schemas/sound/fsl,micfil.yaml#

Fix the warning by describing the clocks up to 'pll8k' as 'clkext3'
is assigned to a dummy clock.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>