spi: ich: Drop while loop in hardware sequencing erase case

spi: ich: Drop while loop in hardware sequencing erase case

When ich_spi_exec_op_hwseq() is called to erase a 4k block
(opcode = SPINOR_OP_BE_4K), it expects to find a length value in
op->data.nbytes, but that value is always 0. As a result, the while loop
is never executed and no erase is carried out.

Fix this by dropping the loop code entirely, only keeping the relevant
parts of the loop body.

See http://patchwork.ozlabs.org/patch/1222779/ for more detailed
background information and discussion.

Signed-off-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>