scsi: ibmvscsis: Increase INITIAL_SRP_LIMIT to 1024

The adapter request_limit is hardcoded to be INITIAL_SRP_LIMIT which is
currently an arbitrary value of 800. Increase this value to 1024 which
better matches the characteristics of the typical IBMi Initiator that
supports 32 LUNs and a queue depth of 32.

This change also has the secondary benefit of being a power of two as
required by the kfifo API. Since, Commit ab9bb631 ("Partially revert
"kfifo: fix kfifo_alloc() and kfifo_init()"") the size of IU pool for each
target has been rounded down to 512 when attempting to kfifo_init() those
pools with the current request_limit size of 800.

Link: https://lore.kernel.org/r/20220322194443.678433-1-tyreld@linux.ibm.comSigned-off-by: NTyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c

@@ -36,7 +36,7 @@
 
 #define IBMVSCSIS_VERSION	"v0.2"
 
-#define	INITIAL_SRP_LIMIT	800
+#define	INITIAL_SRP_LIMIT	1024
 #define	DEFAULT_MAX_SECTORS	256
 #define MAX_TXU			1024 * 1024