[ARM] vfp: fix leak of VFP_NAN_FLAG into FPSCR

The VFP code can leak VFP_NAN_FLAG into the FPSCR. It doesn't correspond
to any real FPSCR bit (and overlaps one of the exception flags).

Bug report from Daniel Jacobowitz
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/vfp/vfpdouble.c

@@ -197,7 +197,7 @@ u32 vfp_double_normaliseround(int dd, struct vfp_double *vd, u32 fpscr, u32 exce
 			 dd, d, exceptions);
 		vfp_put_double(dd, d);
 	}
-	return exceptions & ~VFP_NAN_FLAG;
+	return exceptions;
 }
 
 /*

arch/arm/vfp/vfpmodule.c

@@ -180,7 +180,7 @@ static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
 		 * emulate it.
 		 */
 	}
-	return exceptions;
+	return exceptions & ~VFP_NAN_FLAG;
 }
 
 /*

arch/arm/vfp/vfpsingle.c

@@ -203,7 +203,7 @@ u32 vfp_single_normaliseround(int sd, struct vfp_single *vs, u32 fpscr, u32 exce
 		vfp_put_float(sd, d);
 	}
 
-	return exceptions & ~VFP_NAN_FLAG;
+	return exceptions;
 }
 
 /*