sf: winbond: Correct the nr_blocks used for W25Q32DW

This patch corrected the nr_blocks used for W25Q32DW SPI flash.

nr_blcoks are incorrectly assigned on below patch
"sf: winbond: add W25Q32DW"
(sha1: 772ba154)

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>