staging: sm750fb: change enum dpms to snake_case

Change the entries in `enum dpms` to snake_case in order to conform to
kernel code styles as reported by checkpatch.pl

CHECK: Avoid CamelCase: <crtDPMS_ON>

CHECK: Avoid CamelCase: <crtDPMS_STANDBY>

CHECK: Avoid CamelCase: <crtDPMS_SUSPEND>

CHECK: Avoid CamelCase: <crtDPMS_OFF>

Signed-off-by: Eric Florin <ericflorin.kernel@gmail.com>
Link: https://lore.kernel.org/r/20250423040345.11323-1-ericflorin.kernel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Eric Florin

drivers/staging/sm750fb/ddk750_power.h

@@ -3,10 +3,10 @@
 #define DDK750_POWER_H__
 
 enum dpms {
-	crtDPMS_ON = 0x0,
-	crtDPMS_STANDBY = 0x1,
-	crtDPMS_SUSPEND = 0x2,
-	crtDPMS_OFF = 0x3,
+	CRT_DPMS_ON = 0x0,
+	CRT_DPMS_STANDBY = 0x1,
+	CRT_DPMS_SUSPEND = 0x2,
+	CRT_DPMS_OFF = 0x3,
 };
 
 #define set_DAC(off) {							\