spi: loopback-test: Do not split 1024-byte hexdumps

spi: loopback-test: Do not split 1024-byte hexdumps

spi_test_print_hex_dump() prints buffers holding less than 1024 bytes in
full.  Larger buffers are truncated: only the first 512 and the last 512
bytes are printed, separated by a truncation message.  The latter is
confusing in case the buffer holds exactly 1024 bytes, as all data is
printed anyway.

Fix this by printing buffers holding up to and including 1024 bytes in
full.

Fixes: 84e0c4e5e2c4ef42 ("spi: add loopback test driver to allow for spi_master regression tests")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/37ee1bc90c6554c9347040adabf04188c8f704aa.1746184171.git.geert+renesas@glider.be
Signed-off-by: Mark Brown <broonie@kernel.org>