MA-19031 imx: hab: fix build break

MA-19031 imx: hab: fix build break

Include correct header file to fix below build
break:
  arch/arm/mach-imx/hab.c:20:1: warning: data definition has no type or storage class DECLARE_GLOBAL_DATA_PTR;
  ^~~~~~~~~~~~~~~~~~~~~~~
  arch/arm/mach-imx/hab.c:20:1: warning: type defaults to 'int' in declaration of 'DECLARE_GLOBAL_DATA_PTR' [-Wimplicit-int]
  arch/arm/mach-imx/hab.c:61:17: error: unknown type name 'gd_t'
  static volatile gd_t *gd_save;
  ^~~~
  arch/arm/mach-imx/hab.c: In function 'save_gd':
  arch/arm/mach-imx/hab.c:67:12: error: 'gd'
  undeclared (first use in this function)
  gd_save = gd;
  ^~
  arch/arm/mach-imx/hab.c:67:12: note: each undeclared identifier is reported only once for each function it appears in

Change-Id: Ie8c396be901a80d9bf90b74e59607d6d17619aaa
Signed-off-by: Ji Luo <ji.luo@nxp.com>