ibft: Use IBFT_SIGN instead of open-coding the search string.

We define IBFT_SIGN to "iBFT"; may as well use it.

Signed-off-by: Konrad Rzeszutek Wilk <konrad@kernel.org>
Signed-off-by: Peter Jones <pjones@redhat.com>
diff --git a/drivers/firmware/iscsi_ibft_find.c b/drivers/firmware/iscsi_ibft_find.c
index 82a7a15..2192456 100644
--- a/drivers/firmware/iscsi_ibft_find.c
+++ b/drivers/firmware/iscsi_ibft_find.c
@@ -100,7 +100,7 @@
 	if (!ibft_addr)
 		acpi_table_parse(ACPI_SIG_IBFT, acpi_find_ibft);
 	if (!ibft_addr)
-		acpi_table_parse("iBFT", acpi_find_ibft);
+		acpi_table_parse(IBFT_SIGN, acpi_find_ibft);
 #endif /* CONFIG_ACPI */
 
 	/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will