dropbear: refresh patches

The patch tool will apply patches by default with "fuzz", which is where if the
hunk context isn't present but what is there is close enough, it will force the
patch in.

Whilst this is useful when there's just whitespace changes, when applied to
source it is possible for a patch applied with fuzz to produce broken code which
still compiles (see #10450).  This is obviously bad.

We'd like to eventually have do_patch() rejecting any fuzz on these grounds. For
that to be realistic the existing patches with fuzz need to be rebased and
reviewed.

(From OE-Core rev: 18300f8faa5050178efcd22f2db843f9b3f3bb0f)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/dropbear/dropbear/0004-fix-2kb-keys.patch

@@ -5,18 +5,15 @@ Upstream-Status: Inappropriate [configuration]
  kex.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
 
-diff --git a/kex.h b/kex.h
-index 72430e9..375c677 100644
---- a/kex.h
-+++ b/kex.h
-@@ -67,6 +67,6 @@ struct KEXState {
- };
+Index: dropbear-2017.75/kex.h
+===================================================================
+--- dropbear-2017.75.orig/kex.h
++++ dropbear-2017.75/kex.h
+@@ -106,6 +106,6 @@ int curve25519_donna(unsigned char *out,
+ #endif
  
  
 -#define MAX_KEXHASHBUF 2000
 +#define MAX_KEXHASHBUF 3000
  
- #endif /* _KEX_H_ */
--- 
-1.7.11.7
-
+ #endif /* DROPBEAR_KEX_H_ */