drivers: misc: ti-st: Use int instead of fuzzy char for callback status

On mips and parisc:

    drivers/bluetooth/btwilink.c: In function 'ti_st_open':
    drivers/bluetooth/btwilink.c:174:21: warning: overflow in implicit constant conversion [-Woverflow]
       hst->reg_status = -EINPROGRESS;

    drivers/nfc/nfcwilink.c: In function 'nfcwilink_open':
    drivers/nfc/nfcwilink.c:396:31: warning: overflow in implicit constant conversion [-Woverflow]
      drv->st_register_cb_status = -EINPROGRESS;

There are actually two issues:
  1. Whether "char" is signed or unsigned depends on the architecture.
     As the completion callback data is used to pass a (negative) error
     code, it should always be signed.
  2. EINPROGRESS is 150 on mips, 245 on parisc.
     Hence -EINPROGRESS doesn't fit in a signed 8-bit number.

Change the callback status from "char" to "int" to fix these.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>