clk: microchip: mpfs: update module authorship & licencing

Padmarao wrote the driver in its original, pre upstream form.
Daire & myself have been responsible for getting it upstreamable and
subsequent development.
Move Daire out of the blurb & into a MODULE_AUTHOR entry & add entries
for myself and Padmarao.

While we are at it, convert the MODULE_LICENSE field to its preferred
form of "GPL".

Reviewed-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220909123123.2699583-15-conor.dooley@microchip.com