powerpc/64e: Trivial spelling fixes throughout head_fsl_booke.S

Trivial spelling fixes throughout the file.

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210314220436.3417083-1-unixbhaskar@gmail.com