util/ifdtool: Fix SPI frequency as per Gen11 SPI flash guide

BUG=b:153888802
TEST=Able to list correct SPI frequency as per TGL SPI flash guide

Without this CL :
Found Component Section
FLCOMP     0x093030f6
  Dual Output Fast Read Support:       not supported
  Read ID/Read Status Clock Frequency: 33MHz
  Write/Erase Clock Frequency:         33MHz
  Fast Read Clock Frequency:           33MHz
  Fast Read Support:                   supported
  Read Clock Frequency:                20MHz

With this CL :
Found Component Section
FLCOMP     0x093030f6
  Dual Output Fast Read Support:       not supported
  Read ID/Read Status Clock Frequency: 50MHz
  Write/Erase Clock Frequency:         50MHz
  Fast Read Clock Frequency:           50MHz
  Fast Read Support:                   supported
  Read Clock Frequency:                20MHz

Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Change-Id: Id0a0a0cbd948ef8334cf522c09e881b464e87f0e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44819
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/util/ifdtool/ifdtool.h b/util/ifdtool/ifdtool.h
index fb3de2f..0842924 100644
--- a/util/ifdtool/ifdtool.h
+++ b/util/ifdtool/ifdtool.h
@@ -63,6 +63,14 @@
 	SPI_FREQUENCY_17MHZ = 6,
 };
 
+enum spi_frequency_500_series {
+	SPI_FREQUENCY_100MHZ = 0,
+	SPI_FREQUENCY_50MHZ = 1,
+	SPI_FREQUENCY_500SERIES_33MHZ = 3,
+	SPI_FREQUENCY_25MHZ = 4,
+	SPI_FREQUENCY_14MHZ = 6,
+};
+
 enum component_density {
 	COMPONENT_DENSITY_512KB = 0,
 	COMPONENT_DENSITY_1MB   = 1,