tools/cgdelete: fix coverity wrong argument size warning

tools/cgdelete: fix coverity wrong argument size warning

Fix a wrong argument size, reported by Coverity tool:

CID 1412122 (#1 of 1): Wrong sizeof argument (SIZEOF_MISMATCH)
suspicious_sizeof: Passing argument 8UL
/* sizeof (struct ext_cgroup_record *) */ to function calloc and then
casting the return value to struct ext_cgroup_record * is suspicious.

Also, fix the typo in the variable name, that's being allocated memory.

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>