HSSPI controller uses big endian for the opcode in the message to the
controller ping pong buffer. Use cpu_to_be16 to properly handle the
endianness for both big and little endian host.

Fixes: 142168eb ("spi: bcm63xx-hsspi: add bcm63xx HSSPI driver")
Signed-off-by: Kursad Oney <kursad.oney@broadcom.com>
Signed-off-by: William Zhang <william.zhang@broadcom.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>

Link: https://lore.kernel.org/r/20230207065826.285013-7-william.zhang@broadcom.comSigned-off-by: Mark Brown <broonie@kernel.org>