mtd: spi-nor: fsl-quadspi: fix read error for flash size larger than 16MB

If the size of spi-nor flash is larger than 16MB, the read_opcode
is set to SPINOR_OP_READ_1_1_4_4B, and fsl_qspi_get_seqid() will
return -EINVAL when cmd is SPINOR_OP_READ_1_1_4_4B. This can
cause read operation fail.

Fixes: e46ecda7 ("mtd: spi-nor: Add Freescale QuadSPI driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>