net/sfc/base: fix shift by more bits than field width

[ upstream commit 1dcd3a9 ]

This was probably an oversight when support for multiple sensor pages
was added.

Despite being undefined behaviour in C, it probably worked on Intel
x32/x64 as on them bit shift operations wrap round.

Fixes: dfb3b1c ("net/sfc/base: import monitors access via MCDI")

Signed-off-by: Mark Spender <mspender@solarflare.com>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>

drivers/net/sfc/base/mcdi_mon.c

@@ -73,7 +73,8 @@ mcdi_mon_decode_stats(
 			/* This sensor is one of the page boundary bits. */
 		}
 
-		if (~(sensor_mask[page]) & (1U << sensor))
+		if (~(sensor_mask[page]) &
+		    (1U << (sensor % (sizeof (sensor_mask[page]) * 8))))
 			continue;
 		/* This sensor not in DMA buffer */