net/smc: fix documentation of buffer sizes

Since commit 833bac7 ("net/smc: Fix setsockopt and sysctl to
specify same buffer size again") the SMC protocol uses its own
default values for the smc.rmem and smc.wmem sysctl variables
which are no longer derived from the TCP IPv4 buffer sizes.

Fixup the kernel documentation to reflect this change, too.

Fixes: 833bac7 ("net/smc: Fix setsockopt and sysctl to specify same buffer size again")
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231030170343.748097-1-gbayer@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Gerd Bayer

Documentation/networking/smc-sysctl.rst

@@ -44,18 +44,16 @@ smcr_testlink_time - INTEGER
 
 wmem - INTEGER
 	Initial size of send buffer used by SMC sockets.
-	The default value inherits from net.ipv4.tcp_wmem[1].
 
 	The minimum value is 16KiB and there is no hard limit for max value, but
 	only allowed 512KiB for SMC-R and 1MiB for SMC-D.
 
-	Default: 16K
+	Default: 64KiB
 
 rmem - INTEGER
 	Initial size of receive buffer (RMB) used by SMC sockets.
-	The default value inherits from net.ipv4.tcp_rmem[1].
 
 	The minimum value is 16KiB and there is no hard limit for max value, but
 	only allowed 512KiB for SMC-R and 1MiB for SMC-D.
 
-	Default: 128K
+	Default: 64KiB