doc: board: ti: j7200: provide image alt text

Provide alternative text for image.

Fixes: f4ade09a1e ("doc: board: ti: j7200: Convert the image format to svg")
Reported-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Signed-off-by: Nishanth Menon <nm@ti.com>

doc/board/ti/j7200_evm.rst

@@ -35,6 +35,7 @@ Boot Flow:
 Below is the pictorial representation of boot flow:
 
 .. image:: img/boot_diagram_k3_current.svg
+  :alt: Boot flow diagram
 
 - Here DMSC acts as master and provides all the critical services. R5/A72
   requests DMSC to get these services done as shown in the above diagram.
@@ -130,12 +131,12 @@ Image formats:
 - tiboot3.bin
 
 .. image:: img/j7200_tiboot3.bin.svg
+  :alt: tiboot3.bin image format
 
 - tispl.bin
 
 .. image:: img/dm_tispl.bin.svg
-
-
+  :alt: tispl.bin image format
 
 Switch Setting for Boot Mode
 ----------------------------
@@ -191,6 +192,7 @@ Size of u-boot.img is taken 4MB for refernece,
 But this is subject to change depending upon atf, optee size
 
 .. image:: img/emmc_j7200_evm_boot01.svg
+  :alt: Traditional eMMC boot partition layout
 
 In case of UDA FS mode booting, following is layout.
 
@@ -198,6 +200,7 @@ All boot images tiboot3.bin, tispl and u-boot should be written to
 fat formatted UDA FS as file.
 
 .. image:: img/emmc_j7200_evm_udafs.svg
+  :alt: eMMC UDA boot partition layout
 
 In case of booting from eMMC, write above images into raw or UDA FS.
 and set mmc partconf accordingly.