dt-bindings: power: Rename back power_domain.txt bindings to fix references

With split of power domain controller bindings to power-domain.yaml,
the consumer part was renamed to power-domain.txt breaking the
references. Undo the renaming.

Reported-by: Geert Uytterhoeven <[e-mail]>
Fixes: 5279a3d8bede ("dt-bindings: power: Convert Generic Power Domain bindings to json-schema")
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Ulf Hansson <[e-mail]>
Signed-off-by: Rob Herring <[e-mail]>

MAINTAINERS

···
 S:	Supported
 F:	drivers/base/power/domain*.c
 F:	include/linux/pm_domain.h
-F:	Documentation/devicetree/bindings/power/power-domain*
+F:	Documentation/devicetree/bindings/power/power?domain*
 
 GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER
 M:	Eugen Hristev <[e-mail]>