mtd: msm_qpic_nand: Add support to read one codeword

When the read requests received from upper layer are less
than 516 bytes, then instead of reading the entire page, we
can read only one codeword, thereby improving the read
performance. This support is only applicable if the data
requested lies in first codeword of the page.

Modem KPI markers:
All units in seconds

| Parameter                  | With OCW | W/o OCW | Delta |
| Modem Image Start Loading  | 13.5542  | 14.6176 | 1.0634|
| Modem out of reset         | 19.8452  | 20.9962 | 1.151 |

NAND Perf Stats:
Obtained by reading 1GB data. All units in usec

| Parameter                  | With OCW | W/o OCW | Delta |
| min_read_time_us           | 70       | 340.6   | 270.6 |
| total_read_time_us         | 17737604 | 18603376| 865772|.

Change-Id: I1df9ea7b9193a900b38e3d7a4fe38e2212bbf705
Signed-off-by: Anjana Hari <ahari@codeaurora.org>