No, there is no patch.
But basically it is only one assembler line to change (for Sansa):
/firmware/target/arm/pcm_pp.c:
 change required in #ifdef HAVE_AS3514
  "mov r10, r10, ror #2\n\t" /* put left sample at the top bits */
 to
  "mov r10, r10, ror #18\n\t" /* put right sample at the top bits */
For other PP targets this can be done similarly.
Toni