arm64: Remove gicv3_get_support_lpis

It's no longer used after moving to gic_get_support_lpis.

Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D53665

sys/arm64/arm64/gic_v3.c

@@ -495,7 +495,6 @@ gic_v3_read_ivar(device_t dev, device_t child, int which, uintptr_t *result)
 		*result = (uintptr_t)&sc->gic_redists.pcpu[PCPU_GET(cpuid)];
 		return (0);
 	case GIC_IVAR_SUPPORT_LPIS:
-	case GICV3_IVAR_SUPPORT_LPIS:
 		*result =
 		    (gic_d_read(sc, 4, GICD_TYPER) & GICD_TYPER_LPIS) != 0;
 		return (0);

sys/arm64/arm64/gic_v3_var.h

@@ -108,11 +108,9 @@ MALLOC_DECLARE(M_GIC_V3);
 #define	GICV3_IVAR_NIRQS	1000
 /* 1001 was GICV3_IVAR_REDIST_VADDR */
 #define	GICV3_IVAR_REDIST	1002
-#define	GICV3_IVAR_SUPPORT_LPIS	1003
 
 __BUS_ACCESSOR(gicv3, nirqs, GICV3, NIRQS, u_int);
 __BUS_ACCESSOR(gicv3, redist, GICV3, REDIST, void *);
-__BUS_ACCESSOR(gicv3, support_lpis, GICV3, SUPPORT_LPIS, bool);
 
 /* Device methods */
 int gic_v3_attach(device_t dev);