soc/amd/picasso/chip.h: use boolean type for smt_disable

Even though the UPD field this information is finally written to is an 8
bit value, the smt_disable option is only a boolean.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Iaac49944993a28ffb98a80201effe1238ec60875
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52553
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/picasso/chip.h

@@ -146,7 +146,7 @@ struct soc_amd_picasso_config {
 		DOWNCORE_2 = 3, /* Run with two cores */
 		DOWNCORE_3 = 4, /* Run with three cores */
 	} downcore_mode;
-	uint8_t smt_disable; /* 1=disable SMT, 0=enable SMT */
+	bool smt_disable; /* true=disable SMT on all physical cores */
 
 	/* Lower die temperature limit */
 	uint32_t thermctl_limit_degreeC;