gpio: fix incorrect assignment of *cinfos in mraa_get_chip_infos

*cinfos in mraa_get_chip_infos is not set in case of
mraa_get_chip_info_by_name failure which happens on access of /dev/gpiochip*
files which leads to memory free by invalid pointer in *cinfos.

As example, it can be easy recreated with non-root run of mraa-gpio:

test@iot2050-debian:~$ mraa-gpio
free(): invalid pointer
Aborted

Signed-off-by: Ivan Mikhaylov <ivan.mikhaylov@siemens.com>

src/gpio/gpio_chardev.c

@@ -431,6 +431,8 @@ mraa_get_chip_infos(mraa_gpiod_chip_info*** cinfos)
         return -1;
     }
 
+    *cinfos = cinfo;
+
     /* Get chip info for all gpiochips present in the platform */
     for (i = 0; i < num_chips; i++) {
         cinfo[i] = mraa_get_chip_info_by_name(dirs[i]->d_name);
@@ -440,7 +442,5 @@ mraa_get_chip_infos(mraa_gpiod_chip_info*** cinfos)
         }
     }
 
-    *cinfos = cinfo;
-
     return num_chips;
 }