nvmem: qfprom: Allow single byte accesses for read/write

The nvmem core driver supports to read and write single
byte. So, allow qfprom to support this feature.
This change helps in extracting a required value based
on bit-offset and number of bits for the required value
in the nvmem cell.

Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>