gas: Silence GCC 10 warning on tc-crx.c

gas: Silence GCC 10 warning on tc-crx.c

opcode/crx.h has

typedef enum
  {
    ...
    MAX_REG
  }
reg;

typedef enum
  {
    c0 = MAX_REG,
  }
copreg;

tc-crx.c has

static int
getreg_image (reg r)
{
  ...
 /* Check whether the register is in registers table.  */
  if (r < MAX_REG)
    rreg = &crx_regtab[r];
  /* Check whether the register is in coprocessor registers table.  */
  else if (r < (int) MAX_COPREG)
    rreg = &crx_copregtab[r-MAX_REG];
}

Change getreg_image's argument type to int and replace fragP->fr_literal
with &fragP->fr_literal[0] to silence GCC 10 warning.

	PR gas/26044
	* config/tc-crx.c (getreg_image): Change argument type to int.
	(md_convert_frag): Replace fragP->fr_literal with
	&fragP->fr_literal[0].