mtd: nand: fix GET/SET_FEATURES address on 16-bit devices

As per following Sections in ONFI Spec, GET_FEATURES and SET_FEATURES also need
byte-addressing on 16-bit devices.

*Section: Target Initialization"
"The Read ID and Read Parameter Page commands only use the lower 8-bits of the
 data bus. The host shall not issue commands that use a word data width on x16
 devices until the host determines the device supports a 16-bit data bus width
 in the parameter page."

*Section: Bus Width Requirements*
"When the host supports a 16-bit bus width, only data is transferred at the
 16-bit width. All address and command line transfers shall use only the lower
 8-bits of the data bus. During command transfers, the host may place any value
 on the upper 8-bits of the data bus. During address transfers, the host shall
 set the upper 8-bits of the data bus to 00h."

So porting following commit from linux kernel
    commit e34fcb07a6d57411de6e15a47724fbe92c5caa42
    Author: David Mosberger <davidm@egauge.net>  (preserving authorship)
    mtd: nand: fix GET/SET_FEATURES address on 16-bit devices

Signed-off-by: Pekon Gupta <pekon@ti.com>