cgem: Add support for the SiFive FU740

Note that currently Linux's device tree uses the FU540's compatible
string, as does upstream U-Boot, but the U-Boot shipped with the board
based on an older patch series has the correct FU740 name. Thankfully
they are the same, at least as far as software is concerned.

Whilst here, fix a style(9) nit.

Reviewed by:	philip, kp
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D31034

sys/dev/cadence/if_cgem.c

@@ -105,12 +105,13 @@ __FBSDID("$FreeBSD$");
 #define HWTYPE_GENERIC_GEM	1
 #define HWTYPE_ZYNQ		2
 #define HWTYPE_ZYNQMP		3
-#define HWTYPE_SIFIVE_FU540	4
+#define HWTYPE_SIFIVE		4
 
 static struct ofw_compat_data compat_data[] = {
 	{ "cdns,zynq-gem",		HWTYPE_ZYNQ },
 	{ "cdns,zynqmp-gem",		HWTYPE_ZYNQMP },
-	{ "sifive,fu540-c000-gem",	HWTYPE_SIFIVE_FU540 },
+	{ "sifive,fu540-c000-gem",	HWTYPE_SIFIVE },
+	{ "sifive,fu740-c000-gem",	HWTYPE_SIFIVE },
 	{ "cdns,gem",			HWTYPE_GENERIC_GEM },
 	{ "cadence,gem",		HWTYPE_GENERIC_GEM },
 	{ NULL,				0 }
@@ -1762,8 +1763,7 @@ cgem_attach(device_t dev)
 			    "could not retrieve reference clock.\n");
 		else if (clk_enable(sc->ref_clk) != 0)
 			device_printf(dev, "could not enable clock.\n");
-	}
-	else if (hwtype == HWTYPE_SIFIVE_FU540) {
+	} else if (hwtype == HWTYPE_SIFIVE) {
 		if (clk_get_by_ofw_name(dev, 0, "pclk", &sc->ref_clk) != 0)
 			device_printf(dev,
 			    "could not retrieve reference clock.\n");