[Docs] Fix typo in RGB Matrix Driver configuration (qmk#5182)

* Fix qmk#3797 firmware not compiling

If DRIVER_COUNT 1 firmware will not compile.

* Fix typo

docs/feature_rgb_matrix.md

@@ -67,7 +67,7 @@ Configure the hardware via your `config.h`:
 	#define DRIVER_ADDR_1 0b1010000
 	#define DRIVER_ADDR_2 0b1010000 // this is here for compliancy reasons.
 
-	#define DRIVER_COUNT 1
+	#define DRIVER_COUNT 2
 	#define DRIVER_1_LED_TOTAL 64
 	#define DRIVER_LED_TOTAL DRIVER_1_LED_TOTAL
 
@@ -102,8 +102,8 @@ From this point forward the configuration is the same for all the drivers.
 
 The format for the matrix position used in this array is `{row | (col << 4)}`. The `x` is between (inclusive) 0-224, and `y` is between (inclusive) 0-64. The easiest way to calculate these positions is:
 
-    x = 224 / ( NUMBER_OF_ROWS - 1 ) * ROW_POSITION
-    y = 64 / (NUMBER_OF_COLS - 1 ) * COL_POSITION
+    x = 224 / ( NUMBER_OF_COLS - 1 ) * ROW_POSITION
+    y = 64 / (NUMBER_OF_ROWS - 1 ) * COL_POSITION
 
 Where all variables are decimels/floats.