x86/platform/uv: Fix copied UV5 output archtype

A test shows that the output contains a space:
    # cat /proc/sgi_uv/archtype
    NSGI4 U/UVX

Remove that embedded space by copying the "trimmed" buffer instead of the
untrimmed input character list.  Use sizeof to remove size dependency on
copy out length.  Increase output buffer size by one character just in case
BIOS sends an 8 character string for archtype.

Fixes: 1e61f5a ("Add and decode Arch Type in UVsystab")
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lore.kernel.org/r/20201111010418.82133-1-mike.travis@hpe.com

arch/x86/kernel/apic/x2apic_uv_x.c

@@ -33,7 +33,7 @@ static union uvh_apicid		uvh_apicid;
 static int			uv_node_id;
 
 /* Unpack AT/OEM/TABLE ID's to be NULL terminated strings */
-static u8 uv_archtype[UV_AT_SIZE];
+static u8 uv_archtype[UV_AT_SIZE + 1];
 static u8 oem_id[ACPI_OEM_ID_SIZE + 1];
 static u8 oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1];
 
@@ -320,7 +320,7 @@ static int __init decode_arch_type(unsigned long ptr)
 
 	if (n > 0 && n < sizeof(uv_ate->archtype)) {
 		pr_info("UV: UVarchtype received from BIOS\n");
-		uv_stringify(UV_AT_SIZE, uv_archtype, uv_ate->archtype);
+		uv_stringify(sizeof(uv_archtype), uv_archtype, uv_ate->archtype);
 		return 1;
 	}
 	return 0;
@@ -378,7 +378,7 @@ static int __init uv_set_system_type(char *_oem_id, char *_oem_table_id)
 	if (!early_get_arch_type())
 
 		/* If not use OEM ID for UVarchtype */
-		uv_stringify(UV_AT_SIZE, uv_archtype, _oem_id);
+		uv_stringify(sizeof(uv_archtype), uv_archtype, oem_id);
 
 	/* Check if not hubbed */
 	if (strncmp(uv_archtype, "SGI", 3) != 0) {