memory: renesas-rpc-if: Correct QSPI data transfer in Manual mode

This patch fixes 2 problems:
[1] The output warning logs and data loss when performing
mount/umount then remount the device with jffs2 format.
[2] The access width of SMWDR[0:1]/SMRDR[0:1] register is wrong.

This is the sample warning logs when performing mount/umount then
remount the device with jffs2 format:
jffs2: jffs2_scan_inode_node(): CRC failed on node at 0x031c51d4:
Read 0x00034e00, calculated 0xadb272a7

The reason for issue [1] is that the writing data seems to
get messed up.
Data is only completed when the number of bytes is divisible by 4.
If you only have 3 bytes of data left to write, 1 garbage byte
is inserted after the end of the write stream.
If you only have 2 bytes of data left to write, 2 bytes of '00'
are added into the write stream.
If you only have 1 byte of data left to write, 2 bytes of '00'
are added into the write stream. 1 garbage byte is inserted after
the end of the write stream.

To solve problem [1], data m...