[GCC4] SPARC: fix build error in drivers/fc4/soc.c

[GCC4] SPARC: fix build error in drivers/fc4/soc.c

This patch fixes this error with gcc 4 on sparc :

soc.h: In function 'xram_copy_from':
soc.h:121: error: invalid lvalue in increment
soc.h: In function 'xram_copy_to':
soc.h:128: error: invalid lvalue in increment