mb/google/zork: Switch to normal read mode for EM100

This change sets the EFS config for SPI read mode to normal read mode
when using em100. With this, the boot is stable again without any
random hangs in PSP.

BUG=b:164429022

Signed-off-by: Furquan Shaikh <furquan@google.com>
Change-Id: I4cd3673dcc44a61905719a57f734df2fb9f4e6e2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44464
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt Papageorge <matthewpapa07@gmail.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/google/zork/Kconfig

@@ -244,13 +244,13 @@ config VBOOT_STARTS_IN_BOOTBLOCK
 
 config EFS_SPI_READ_MODE
 	int
-	default 4 if EM100
-	default 2
+	default 0 if EM100 # Normal read mode
+	default 2          # Dual IO (1-1-2)
 
 config EFS_SPI_SPEED
 	int
-	default 3 if EM100
-	default 0
+	default 3 if EM100 # 16.66 MHz
+	default 0          # 66.66 MHz
 
 config EFS_SPI_MICRON_FLAG
 	int