sf: Update sf read to support all sizes of flashes

sf: Update sf read to support all sizes of flashes

This patch updated the spi_flash read func to support all
sizes of flashes using bank reg addr facility.

The same support has been added in below patch for erase/write
spi_flash functions:
"sf: Support all sizes of flashes using bank addr reg facility"
(sha1: c956f600cbb0943d0afe1004cdb503f4fcd8f415)

With these new updates on sf framework, the flashes which has < 16MB
are not effected as per as performance is concern and but the
u-boot.bin size incrased ~460 bytes.

sf update(for first 16MBytes), Changes before:
U-Boot> sf update 0x1000000 0x0 0x1000000
- N25Q256
  16777216 bytes written, 0 bytes skipped in 199.72s, speed 86480 B/s
- W25Q128BV
  16777216 bytes written, 0 bytes skipped in 351.739s, speed 48913 B/s
- S25FL256S_64K
  16777216 bytes written, 0 bytes skipped in 65.659s, speed 262144 B/s

sf update(for first 16MBytes), Changes before:
U-Boot> sf update 0x1000000 0x0 0x1000000
- N25Q256
  16777216 bytes written, 0 bytes skipped in 198.953s, speed 86480 B/s
- W25Q128BV
  16777216 bytes written, 0 bytes skipped in 350.90s, speed 49200 B/s
- S25FL256S_64K
  16777216 bytes written, 0 bytes skipped in 66.521s, speed 262144 B/s

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>