cpu: Fix spelling

Change-Id: I69c46648de0689e9bed84c7726906024ad65e769
Signed-off-by: Martin Roth <martin.roth@se-eng.com>
Reviewed-on: http://review.coreboot.org/3729
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/x86/car.c

@@ -33,7 +33,7 @@ extern char _car_data_end[];
 
 /*
  * The car_migrated global variable determines if the cache-as-ram space has
- * been migrated to real RAM. It does this by asumming the following things:
+ * been migrated to real RAM. It does this by assuming the following things:
  *   1. cache-as-ram space is zero'd out once it is set up.
  *   2. Either the cache-as-ram space is memory-backed after getting torn down
  *      or the space returns 0xff's for each byte read.