eiger: quad write/read reg (dr) and quad positions (#649)

* eiger: adding mask to read/write registers. useful for setting quad parameters as they might have different values for left and right fpga registers.
** fix quad position
* fix quad flipping
* formatting

slsDetectorServers/eigerDetectorServer/Beb.c

@@ -1106,7 +1106,9 @@ int Beb_SetDetectorPosition(int pos[]) {
     int posRight[2] = {Beb_top ? pos[X] + 1 : pos[X], pos[Y]};
 
     if (Beb_quadEnable) {
-        posRight[Y] = 1; // right is next row
+        posLeft[Y] = 1;  // left is next row
+        posLeft[X] = 0;  // left same first row
+        posRight[Y] = 0; // right same first row
         posRight[X] = 0; // right same first column
     }