recovery: fix building with pointer-to-int errors turned on

Use intptr_t/uintptr_t to cast between pointer and int to allow
building with -Werror=pointer-to-int-cast and
Werror=int-to-pointer-cast turned on.

Cast to char* instead of unsigned int for pointer arithmetic.

Change-Id: Ia862306fdcca53866b330e8cf726f3d62f2248a0
diff --git a/minui/graphics.c b/minui/graphics.c
index d757165..a2014dc 100644
--- a/minui/graphics.c
+++ b/minui/graphics.c
@@ -157,7 +157,7 @@
     fb->width = vi.xres;
     fb->height = vi.yres;
     fb->stride = fi.line_length/PIXEL_SIZE;
-    fb->data = (void*) (((unsigned) bits) + vi.yres * fi.line_length);
+    fb->data = (void*) (((char*) bits) + vi.yres * fi.line_length);
     fb->format = PIXEL_FORMAT;
     memset(fb->data, 0, vi.yres * fi.line_length);