lib/oe/recipeutils: Avoid wrapping any SRC_URI[sha*sum] variables

lib/oe/recipeutils: Avoid wrapping any SRC_URI[sha*sum] variables

Before, a variable such as SRC_URI[sha512sum] would end up as:

SRC_URI[sha512sum] = "45ff3abce4dab24a8090409e6d7bb26afa7fa7812a51e067 \
28c2aa47d5b4de610d97ba4609cf13d9173087bd909fdf377235eee988a6fdcf52abb7 \
0341c40b5b"

when updated by patch_recipe_lines().

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>