nvmem: lan9662-otp: Fix compatible string

The device tree bindings for lan9662-otp expects the compatible string
to be one of following compatible strings:
microchip,lan9662-otpc
microchip,lan9668-otpc

The problem is that the lan9662-otp driver contains the
microchip,lan9662-otp compatible string instead of
microchip,lan9662-otpc.
Fix this by updating the compatible string in the driver.

Fixes: 9e8f208a

 ("nvmem: lan9662-otp: add support")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20220928195112.630351-1-horatiu.vultur@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>