staging: comedi: amplc_pci230: Convert macro GAT_CONFIG to static inline function

Convert macro GAT_CONFIG to static inline function as static inline
functions are preferred over macros. This change is possible since the
arguments at all call sites have the same type.

This was done using Coccinelle:

@r@
expression e;
@@
- #define GAT_CONFIG(chan, src) e
+ static inline unsigned int pci230_gat_config(unsigned int chan,
+                                              unsigned int src)
+{
+       return ((chan & 3) << 3) | (src & 7);
+}

@r1@
expression dev,reg,chan,src;
@@
-GAT_CONFIG(chan, src)
+pci230_gat_config(chan, src)

Also, the comment describing the macro has been removed manually.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>