spi: fsl_qspi: Fix qspi_op_rdid memcpy issue

spi: fsl_qspi: Fix qspi_op_rdid memcpy issue

In current driver everytime we memcpy 4 bytes to the dest memory
regardless of the remaining length.
This patch adds checking the remaining length before memcpy.
If the length is shorter than 4 bytes, memcpy the actual length of data
to the dest memory.

Signed-off-by: Gong Qianyu <Qianyu.Gong@freescale.com>
Reviewed-by: York Sun <york.sun@nxp.com>