systemd-boot: Remove -mfpmath=sse option from cflags

EFI sources in systemd uses -mgeneral-regs-only which conflicts
with -mfpmath=sse specified by OE via tune arguments. It needs to
be removed, clang errors about it and fails the build

Fixes
error: the 'sse' unit is not supported with this instruction set

(From OE-Core rev: a7cbb7b90a9eb9f8a98054f8613a8230472cf4a5)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/systemd/systemd-boot_257.5.bb

@@ -47,6 +47,11 @@ FILES:${PN} = "${EFI_FILES_PATH}/${SYSTEMD_BOOT_IMAGE}"
 
 RDEPENDS:${PN} += "virtual-systemd-bootconf"
 
+# efi portions use -mgeneral-regs-only option which conflicts with SSE
+# especially clang throws errors about it
+# error: the 'sse' unit is not supported with this instruction set
+TUNE_CCARGS:remove = "-mfpmath=sse"
+
 CFLAGS:append:libc-musl = " -D__DEFINED_wchar_t"
 
 COMPATIBLE_HOST = "(aarch64.*|arm.*|x86_64.*|i.86.*|riscv.*)-linux"