apalis_t30: colibri_imx7: colibri_t30: fix ethernet functionality

Since commit aa7a648747d8c704a9a81c9e493d386930724e9d
("net: Stop including NFS overhead in defragment max") the following
has been reproducibly observed while trying to transfer data over TFTP:

Load address: 0x80408000
Loading: EHCI timed out on TD - token=0x8008d80
T EHCI timed out on TD - token=0x88008d80
Rx: failed to receive: -5

This patch fixes this by lowering our TFTP block size to be within the
standard maximal de-fragmentation aka IP packet size again.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
diff --git a/include/configs/apalis_t30.h b/include/configs/apalis_t30.h
index 8c76605..3fc1779 100644
--- a/include/configs/apalis_t30.h
+++ b/include/configs/apalis_t30.h
@@ -52,7 +52,7 @@
 
 /* General networking support */
 #define CONFIG_IP_DEFRAG
-#define CONFIG_TFTP_BLOCKSIZE		16384
+#define CONFIG_TFTP_BLOCKSIZE		16352
 #define CONFIG_TFTP_TSIZE
 
 /* Miscellaneous commands */