GCN: Add pre-initial support for gfx1100: 'EF_AMDGPU_MACH_AMDGCN_GFX1100'

    ../../../source-gcc/libgomp/plugin/plugin-gcn.c: In function ‘isa_hsa_name’:
    ../../../source-gcc/libgomp/plugin/plugin-gcn.c:1666:10: error: ‘EF_AMDGPU_MACH_AMDGCN_GFX1100’ undeclared (first use in this function); did you mean ‘EF_AMDGPU_MACH_AMDGCN_GFX1030’?
     1666 |     case EF_AMDGPU_MACH_AMDGCN_GFX1100:
          |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          |          EF_AMDGPU_MACH_AMDGCN_GFX1030
    ../../../source-gcc/libgomp/plugin/plugin-gcn.c:1666:10: note: each undeclared identifier is reported only once for each function it appears in
    ../../../source-gcc/libgomp/plugin/plugin-gcn.c: In function ‘isa_code’:
    ../../../source-gcc/libgomp/plugin/plugin-gcn.c:1711:12: error: ‘EF_AMDGPU_MACH_AMDGCN_GFX1100’ undeclared (first use in this function); did you mean ‘EF_AMDGPU_MACH_AMDGCN_GFX1030’?
     1711 |     return EF_AMDGPU_MACH_AMDGCN_GFX1100;
          |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          |            EF_AMDGPU_MACH_AMDGCN_GFX1030
    ../../../source-gcc/libgomp/plugin/plugin-gcn.c: In function ‘max_isa_vgprs’:
    ../../../source-gcc/libgomp/plugin/plugin-gcn.c:1728:10: error: ‘EF_AMDGPU_MACH_AMDGCN_GFX1100’ undeclared (first use in this function); did you mean ‘EF_AMDGPU_MACH_AMDGCN_GFX1030’?
     1728 |     case EF_AMDGPU_MACH_AMDGCN_GFX1100:
          |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          |          EF_AMDGPU_MACH_AMDGCN_GFX1030
    make[4]: *** [Makefile:813: libgomp_plugin_gcn_la-plugin-gcn.lo] Error 1

Fix-up for commit 52a2c659
"GCN: Add pre-initial support for gfx1100".

	libgomp/
	* plugin/plugin-gcn.c (EF_AMDGPU_MACH): Add
	'EF_AMDGPU_MACH_AMDGCN_GFX1100'.