net: filter: Fix some more small issues in sparc JIT.

Fix mixed space and tabs.

Put bpf_jit_load_*[] externs into bpf_jit.h

"while(0)" --> "while (0)"
"COND (X)" --> "COND(X)"
Document branch offset calculations, and bpf_error's return
sequence.

Document the reason we need to emit three nops between the
%y register write and the divide instruction.

Remove erroneous trailing semicolons from emit_read_y() and
emit_write_y().

Based upon feedback from Sam Ravnborg.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/net/bpf_jit_asm.S b/arch/sparc/net/bpf_jit_asm.S
index 46d8f59..9d016c7 100644
--- a/arch/sparc/net/bpf_jit_asm.S
+++ b/arch/sparc/net/bpf_jit_asm.S
@@ -195,5 +195,11 @@
 	 sll	r_OFF, 2, r_X
 
 bpf_error:
+	/* Make the JIT program return zero.  The JIT epilogue
+	 * stores away the original %o7 into r_saved_O7.  The
+	 * normal leaf function return is to use "retl" which
+	 * would evalute to "jmpl %o7 + 8, %g0" but we want to
+	 * use the saved value thus the sequence you see here.
+	 */
 	jmpl	r_saved_O7 + 8, %g0
 	 clr	%o0