leds: qti-flash: Fix debug prints, read more than one byte

Print the data instead of the pointer in qti_flash_led_write(), update
the print in qti_flash_led_masked_write(), and fix qti_flash_led_read()
so that it returns a pointer to more than one byte.

Change-Id: Ic9cbc35a6552f8978ff9e36da2aafeec69885b9a
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>