serial: pl011: Spelling s/clocks-names/clock-names/

	   must correspond to the PCLK clocking the internal logic

	   of the block. Just listing one clock (the first one) is

	   deprecated.

- clocks-names:

- clock-names:

	   When present, the first clock listed must be named

	   "uartclk" and the second clock listed must be named

	   "apb_pclk"