liblzma: Fix a comment in the RISC-V filter.

src/liblzma/simple/riscv.c

@@ -320,11 +320,11 @@ AUIPC with rd == x0
 // The left-hand side takes care of (1) and (2).
 //   (a) The lowest 7 bits are already known to be AUIPC so subtracting 0x17
 //       makes those bits zeros.
-//   (b) If AUIPC rd equals x2, subtracting 0x10 makes bits [11:7] zeros.
+//   (b) If AUIPC rd equals x2, subtracting 0x100 makes bits [11:7] zeros.
 //       If rd doesn't equal x2, then there will be at least one non-zero bit
 //       and the next step (c) is irrelevant.
 //   (c) If the lowest two opcode bits of the packed inst2 are set in [13:12],
-//       then subtracting 0x300 will make those bits zeros. Otherwise there
+//       then subtracting 0x3000 will make those bits zeros. Otherwise there
 //       will be at least one non-zero bit.
 //
 // The shift by 18 removes the high bits from the final '>=' comparison and