NTB: ntb_perf: fix printing of resource_size_t

On 32-bit architectures, resource_size_t is usually 'unsigned int' or
'unsigned long' but not 'unsigned long long', so we get a warning
about printing the wrong data:

drivers/ntb/test/ntb_perf.c: In function 'perf_setup_peer_mw':
drivers/ntb/test/ntb_perf.c:1390:35: error: format '%llx' expects argument of type 'long long unsigned int', but argument 4 has type 'resource_size_t {aka unsigned int}' [-Werror=format=]

This changes the format string to the special %pa that is already
used elsewhere in the same file.

Fixes: b83003b3fdc1 ("NTB: ntb_perf: Add full multi-port NTB API support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jon Mason <jdmason@kudzu.us>