can: sja1000_isa: fix "limited range" compiler warnings
can: sja1000_isa: fix "limited range" compiler warnings

This patch fixes the compiler warnings: "comparison is always
false due to limited range of data type" by using "0xff" instead
of "-1" for unsigned values.

Signed-off-by: Wolfgang Grandegger <5aa1976eca1fee4e35c7b71ec8e8a0ebad9da3d1@grandegger.com>
Acked-by: Marc Kleine-Budde <4a0ea1158d3cc63151119c05b1bff00c0bdbf421@pengutronix.de>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas