powerpc/epapr: Fix parmeters typo

s/parmeters/parameters/

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210320213932.22697-1-unixbhaskar@gmail.com