MAINTAINERS: add self as reviewer for AXI PWM GENERATOR

The initial author of the driver has moved on, so add the final
submitter (myself) as reviewer for the AXI PWM driver.

Signed-off-by: Trevor Gamblin <[email protected]>
Reviewed-by: Nuno Sa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Uwe Kleine-König <[email protected]>

Author: threexc

MAINTAINERS

@@ -3758,6 +3758,7 @@ F:	drivers/spi/spi-axi-spi-engine.c
 AXI PWM GENERATOR
 M:	Michael Hennerich <[email protected]>
 M:	Nuno Sá <[email protected]>
+R:	Trevor Gamblin <[email protected]>
 L:	[email protected]
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers