RISC-V: Add missing disassembler option max

The flag already exists but it's not been exposed to user.

Signed-off-by: Marek Pikuła <m.pikula@partner.samsung.com>

binutils/doc/binutils.texi

@@ -2701,6 +2701,14 @@ but the result again may not be as you expect.
 For RISC-V, the following options are supported:
 
 @table @code
+@item max
+Disassemble without checking architecture string. This is a best effort mode, so
+for overlapping ISA extensions the first match (possibly incorrect in a given
+context) will be used to decode the instruction. It's useful, if the ELF file
+doesn't expose ISA string, preventing automatic ISA subset deduction, and the
+default fallback ISA string (@code{rv64gc}) doesn't cover all instructions in
+the binary.
+
 @item numeric
 Print numeric register names, rather than ABI names (e.g., print @code{x2}
 instead of @code{sp}).

opcodes/riscv-dis.c

@@ -69,7 +69,7 @@ struct riscv_private_data
   const char (*riscv_fpr_names)[NRC];
   /* If set, disassemble as most general instruction.  */
   bool no_aliases;
-  /* If set, disassemble without checking architectire string, just like what
+  /* If set, disassemble without checking architecture string, just like what
      we did at the beginning.  */
   bool all_ext;
 };
@@ -83,6 +83,7 @@ set_default_riscv_dis_options (struct disassemble_info *info)
   pd->riscv_gpr_names = riscv_gpr_names_abi;
   pd->riscv_fpr_names = riscv_fpr_names_abi;
   pd->no_aliases = false;
+  pd->all_ext = false;
 }
 
 /* Parse RISC-V disassembler option (without arguments).  */
@@ -1580,6 +1581,9 @@ static struct
   riscv_option_arg_t arg;
 } riscv_options[] =
 {
+  { "max",
+    N_("Disassemble without checking architecture string."),
+    RISCV_OPTION_ARG_NONE },
   { "numeric",
     N_("Print numeric register names, rather than ABI names."),
     RISCV_OPTION_ARG_NONE },