sparc: don't #include asm/system.h in asm/jump_label.h

It seems that #include <asm/system.h> makes a circular dependency
between kernel.h and bitmap.h which breaks allmodconfig build.
Removing the line makes no change because jump_label.h doesn't
need it actually AFAICS. Compile tested on sparc32 allmodconfig.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>