net/smc: fix valid DMBE buffer sizes

The SMCD_DMBE_SIZES should include all valid DMBE buffer sizes, so the
correct value is 6 which means 1MB. With 7 the registration of an ISM
buffer would always fail because of the invalid size requested.
Fix that and set the value to 6.

Fixes: c6ba7c9b ("net/smc: add base infrastructure for SMC-D and ISM")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/smc/smc_core.c

@@ -1597,7 +1597,7 @@ static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
 	return rc;
 }
 
-#define SMCD_DMBE_SIZES		7 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */
+#define SMCD_DMBE_SIZES		6 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */
 
 static struct smc_buf_desc *smcd_new_buf_create(struct smc_link_group *lgr,
 						bool is_dmb, int bufsize)